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THE 


First  Book  of  Knowledge 


BY 

FREDERICK  GUTHRIE,  F.R.S. 

Professok  of  Physics  at  the  Normal  School  of  Science 
South  Kensington 


NEW  YORK 
G.    P.    PUTNAM'S    SONS 

27  AND  29  WEST  23D  STREET 
1882 


INTRODUCTORY. 


WHAT  THIS  BOOK  IS  ABOUT,  AND  HOW  TO  USE  IT. 


Clay  is  a  stuff.  A  brick  is  a  thing.  I  want  boys  and 
girls,  and  so,  by-and-by,  everybody,  to  know  something 
about  stuffs  and  things.  Therefore,  in  this  First  Book  of 
Knowledge  I  have  striven  to  make  clear  what  stuffs  are, 
and  how  things  are  made  from  them.  So  I  take  such  a 
house  as  most  of  us  live  in,  and  show,  first,  of  what  stuffs, 
and  how,  its  parts  are  made,  and  I  speak  as  near  to  the 
beginning  as  I  can  of  those  things  which  are  first  used  as 
the  house  is  being  built.  But  as  I  find  that  bricks  and 
mortar  are  made  by  the  help  of  coal,  I  begin  with  a  few 
words  about  coal ;  then  I  speak  of  what  may  be  called 
the  trimmings  of  the  house — such  as  paint  and  paper; 
then  of  pots,  and  pans,  and  such;  then  of  lighting  and 
heating,  then  of  clothing,  then  of  food,  then  of  cleaning, 
then  of  writing  and  printing. 

When  this  book  is  used  by  a  teacher,  he  should  get  as 
many  as  he  can  of  the  stuffs  and  things  spoken  of — such 
as  a  lump  of  clay,  a  brick,  a  bit  of  lime,  a  bit  of  iron  ore, 
a  bit  of  iron,  and  so  on.  Lists  of  such  things  are  given  as 
they  are  wanted.     Each  Part  of  the  Book  is  broken  into 


4  INTRODUCTORY. 

lesser  parts  marked  by  numbers,  such  as  IX.  Eacli  lesser 
part  forms  about  one  Lesson.  The  Questions  given  at 
the  end  of  each  lesson  are  only  samples.  As  the  teacher 
gets  further  on,  he  will  of  course  ask  questions  about  what 
has  gone  before.  In  teaching,  he  should  only  use  this 
book  as  a  guide,  and  he  should  be  able  to  give  other  and 
more  knowledge  than  is  given  here. 

No  one  man  or  woman  can  fully  understand  all  these 
things ;  so  I  have  asked  some  of  my  friends  to  help  me 
in  those  parts  which  they  best  know,  and  I  have  got 
some  children  to  help  me  in  the  same  way.  My  thanks 
are  chiefly  due  to  the  following  : — Dr.  J.  H.  Gladstone, 
F.R.S.;  Mr.  T.  Healey,  Professor  Judd,  F.R.S.;  Professor 
Eoberts,  F.R.S.;  the  Misses  J.  and  L.  Sharpe,  and  Mr. 
J.  Harris  Stone,  M.A. 

I  shall  be  glad  to  hear  from  anyone  who  has  anything 
to  say  about  the  book  as  to  how  it  might  be  bettered; 
and,  although  I  may  not  be  able  to  answer  them,  I  shall 
take  care  that  what  they  may  say  shall  be  well  weighed 
for  use  in  other  editions. 

FREDERICK  GUTHRIE. 
South  Kensington,  1881. 


CONTENTS. 


PAET    I. 

THINGS   AND   STUFFS   USED  FOE  HOUSE   BUILDING. 

PAGE 

I. — Coal,  Ashes,  Cinders,  Coke,  Breeze,      .  .  .9 

II. — Concrete,  Mortar,     .  .  .  .  11 

III. — Bricks,  Clay,  Tiles,  Chimney-pots,  Drain-pipes,  .     12 

IV. — Limestone,     Marble,     Sandstone,     Granite,     Plaster, 

Thatch,  Shingles,  .  .  .  .  .15 

V. — Metals  in  general,  Iron,  Slag,  ...  17 

VI. — Lead,  Zinc,  Copper,  Brass,  Tin,  Mercury,  Tin-plate, 

Zinc-plate,  Galvanised  Iron,  .  .  .20 

VII.— Glue,  Whitewash,  Glass,  Litharge,  Putty,  .  24 

(For  Wood,  see  Part  III.,  page  42.) 


PAET    II. 

"WHAT  MATTER  IS  MADE  OF. 

ELEMENTS.     AIR.     FIRE.     FLAME.     WATER. 

VITL— Elements,  Air,  .             .             .             .             .  .27 

IX.— Fire,              ......  30 

X. — Fire,  Flame,  Soot,  Lamp-black,             ,             ,  .32 

XL— Flame,          ......  35 

XII.— Water,                .             .             •            .             .  .37 

XIIL— Water  (continued),               .            .            »  39 


CONTENTS. 

PART    III. 

WOOD. 
XIV. — Wood.     Its  growth.     Different  kinds,        .  .     42 

XV.— Wood— Planks,    Deals,    Battens,    Tressels,  Joists, 

Laths,  Veneer,      .  .  .  .  .45 


P  A  E  T    I  Y. 

HEATING   AND   LIGHTING. 
XVI. — Charcoal,  Peat,  Coal-gas,     .  .  .  .48 

XVII. — Candles  —  Tallow,     Wax,     Spermaceti,     Stearine, 

Composite,  Paraffin,  Glycerine,  .  .  50 

XVIII.— Oils,  Petroleum,  Train  Oil,  Seal  Oil,  Porpoise  Oil, 
Sperm  Oil,  Colza  Oil,  Cocoa-nut  Oil,   Matches, 
Sulphur,   .  .  .  .  .  .53 

XIX. — Matches,     Phosphorus,    Nitre,    Nitrate    of    Soda, 

Chlorate  of  Potash,     .  ...  55 

XX. — Lighting  a  Match,  or  Striking  a  Light,       .  ,     58 


PAET    y. 

FINISHING   AND   FURNISHING. 

XXL— Cotton,  Wadding,   Thread,   Warp,  Woof,    Muslin, 

Flax,  Linen,  Tow,  Hemp,  .  .  .61 

XXII.— Paper,     ......  64 

XXIII. — Paints,  Linseed  Oil,  White  Lead,  Zinc-white,         .     67 
XXIV. — Colours   of   Wall-papers,    Cane,    Pushes,   Wicker, 

Horse  Hair,     .....  70 

XXV. — Varnish,  Turpentine,  Magnesia,  Gum  Copal,  Resin, 
Shell-lac,    Spirits    of    Wine,    Gum    Sandarach, 
Lacquer,    ...  .  .     72 

XXVI. — Woollen,     Worsted,      Carpets,    Cocoa-nut    -Fibre, 

Looking-glasses  (or  Mirrors),  .  .  75 

XXVII. — German  Silver,  Nickel,  Britannia  Metal,  Antimony, 

Silver,       .  .  .  .  .  .78 

XXVIII. — Plate,  Silver-plate,  Silvering,  Electro-plating,  .  80 

XXIX. — Steel,  Tempering,  Pewter,  Enamel,  Borax,  .     82 

XXX. — Pottery,  Crockery,  Earthenware,  Porcelain,  Felspar,     84 


CONTENTS.  7 

PART    VI. 
CLOTHING. 

PAGE 

XXXI.—  Broadcloth,  Fuller's  Earth,  Fulling,  Teasel,  Felt,     86 
XXXII.  —  Silk,  Satin,   Velvet,    Velveteen,  Fustian,  Serge, 

Kerseymere,  Merino,  Crape,  Alpaca,  Straw,     .     88 
XXXIII. — Leather,  Tanning,  Gelatine,  Tannin,  Tan,  Currier, 
Kid,  Wash-Leather,  Chamois  (Shamoy),  Black- 
ing,      .  .  .  .  .  .90 

XXXIV. — Fur,  Combs,  Tortoiseshell,  Ebonite,  Pins,  Draw- 
plate,  Cream  of  Tartar,  Tartaric  Acid,  Brooms, 
Brushes,  Broom,  Bast,        ...  93 

XXXV.— Needles 96 


PART    VII. 

FOOD. 

XXX VI.— Bread,  Sheaves,  Chaff,  Winnowing,  Bran,  Bolt- 
ing, Gluten,       .  .  .  .  .98 
XXXVII. — Fermentation,  Yeast,  Barm,  Glucose,   Dextrine, 

Leaven,  iErated  Bread,  Biscuits,  Oatmeal,  100 

XXXVIII.— Milk,  Cream,  Butter,  Cheese,  Whey,  Rennet,      .  102 
XXXIX. — Beer,  Sprouting  or  Germination,  Malt,  Mashing, 

Mash,  Grains,  Wort,  Hops,  Alcohol,  .  105 

XL. — Salt  (table),  Sugar,  Treacle,  Molasses,  Vinegar,     .  107 


PART     VIII. 

CLEANING. 

XLI. — Soap — Hard  Soap,  Soft  Soap.    Soda — Carbonate  of 
Soda,  Washing-soda.  Bicarbonate  of  Soda.    Hy- 
drochloric Acid  (Muriatic  Acid,  Spirit  of  Salt),  110 
XLII. — Cleaning  Furniture,  Hearthstone  Flanders  Brick, 

Bath  Brick,  Sponge,  Starch,  Prussian  Blue,  113 
XLIII. — Oil  of  Vitriol,  Sulphuric  Acid,  Nitric  Acid 
(Aqua-fortis),  Pumice-stone,  Cleaning  Silver, 
Rouge,  Cleaning  Iron  and  Steel,  Emery,  Rotten- 
stone,  Tripoli -powder,  Chloride  of  Lime, 
Bleaching-powder,        ....  116 


PAGE 


O  CONTENTS. 

P  A  E  T     IX. 

WRITING   AND   PRINTING. 
XLIV.—  Writing,  Pens,  Gall   Nuts,  Copperas  (Green  Vitriol 
or  Sulphate  of  Iron),  Red  Ink,  Blue  Ink,  Oxalic 

_____  Acid> 119 

XL  V.— Black-lead,  Plumbago,  Graphite,  India-rubber  (Caout- 
chouc), Sealing-wax,  Gum-Arabic,  British  Gum 
(Dextrine),  .  .  .  #  122 

XLVI.—  Printing,  Type,  Antimony,  Printers'  Ink,      ,  .  124 

Index,        .......        127 


PART    I. 


THINGS  AND  STUFFS  USED  FOR  HOUSE- 
BUILDING. 

I. 

Coal,  Ashes,  Cinders,  Coke,  Breeze. 

Things  to  be  Seen. — A  piece  of  coal — a  piece  of  lime- 
stone— a  piece  of  coal  with  some  plant  remains  in 
it — a  piece  of  limestone  with  some  shells  in  it — 
ashes,  cinders,  coke,  and  breeze. 

§  1.  Coal. — When  wood  or  woody  matter — such  as 
roots,  bark,  leaves,  moss,  peat,  and  so  on — lies  buried  in 
the  earth  for  a  very  long  time,  it  changes  into  coal. 
Wherever  coal  is  now  found,  there  were  once  forests,  or 
woods,  or  peat,  or  else  mouths  of  rivers,  or  other  places 
where  plants  grew,  or  their  dead  parts,  leaves  and 
branches  and  roots,  got  heaped  together.  Then  such 
places  got  covered  with  water,  often  because  they  sank 
below  the  level  of  the  sea,  and  the  sea  covered  them,  and 
they  were  at  the  bottom  of  the  sea.  Then  the  mud 
which  rivers  bring  down  to  the  sea  sank  down  and 
covered  them,  and  the  shells  and  skeletons  of  dead  sea 
animals  fell  also  upon  them,  so  that  they  got  covered 
deeper  and  deeper.  When  such  places  rose  again  above 
the  sea-level,  the  sea  rolled  off  them,  and  the  rain  washed 
the  sea-salt  off  them,  so  that  when  the  wind  blew  seeds 
upon  them,  the  seeds  struck  root,  and  plants  again  grew. 
This  sinking  and  rising  of  the  earth  has  sometimes  hap- 


10  ASHES,  CINDERS,  COKE,  BREEZE. 

pened  many  times  in  the  same  place.  So  that  on  digging 
down  we  often  come  upon  several  layers  of  coal,  called 
seams  of  coal;  and  hetween  the  separate  seams  is  the 
earth  which  once  formed  the  bottom  of  the  sea,  and 
which  has  got  hardened  into  rocks.  Sometimes  a  part 
of  the  land  on  which  plants  grew  has  sunk  down  and 
formed  a  hollow  or  basin  so  far  from  the  sea  that  the  sea 
has  not  rolled  in  upon  it.  Such  hollows  have  then  got 
filled  with  water  from  rivers  and  rain,  and  have  become 
lakes.  Then,  as  before,  mud  has  settled  upon  the  bottom, 
along  with  the  shells  and  skeletons  of  fresh- water 
animals  ;  and  so  this  may  go  on  again  and  again.  So  the 
plants  have  got  buried,  and,  after  thousands  and  thou- 
sands of  years,  have  become  coal.  Of  course,  therefore, 
when  one  seam  of  coal  lies  above  another,  the  upper  one 
has  been  formed  last,  and  pieces  of  such  newer  coal  often 
have  the  shapes  which  they  had  when  they  were  buried, 
such  as  tree-trunks  and  seed.  But  such  plants  are  often 
unlike  those  now  growing  above  them ;  and  this  shows 
either  that  the  climates  of  countries  have  changed  very 
much,  or  that  the  plants  themselves  have  gradually 
altered  through  one  plant  not  being  quite  like  the'  plant 
from  whose  seed  it  sprang. 

§  2.  Ashes,  Cinders,  Coke,  Breeze. — When  coal  is 
thoroughly  burnt  in  an  open  fireplace,  nothing  is  left  but 
ashes,  which  are  nearly  white,  and  very  soft  and  light. 
"When  coal  is  not  thoroughly  burnt,  it  is  cinder.  The 
stuff  which  falls  through  the  bars  is  partly  ash  and  partly 
cinder.  If  this  mixture  is  put  on  a  sieve  and  sifted,  the 
ashes  fall  through  and  leave  the  cinders.  When  coal  is 
baked  in  an  iron  box  which  has  a  hole  in  it,  a  lot  of  gas 
(see  §  40)  and  tar  comes  out  of  the  hole ;  and  when  the 
box  has  got  cold  and  is  opened,  a  hard,  gritty,  black  mass 
is  found,  which  is  called  Coke.  When  broken  into 
small  pieces,  coke  is  called  Breeze.  Both  coke  and  breeze 
can  be  burnt  in  an  open  fireplace,  and  they  leave  behind 
just  the  same  ash  that  coal  does, 


CONCRETE.  11 

Questions. — What  has  coal  been  made  of?  How  has  it  1>een 
made  ?  How  does  it  come  that  coal  is  found  in  "  senilis" — that  is, 
layers — between  which  there  are  layers  of  rock?  Why  are  shells 
often  found  in  such  layers  of  rock  ?  How  is  it  that  the  remains  of 
plants  found  in  coal  belong  to  plants  unlike  those  now  growing  ou 
the  ground  above  the  coal  ?  What  is  left  when  coal  is  thoroughly 
burnt  ?  What  is  left  when  it  is  only  partly  burnt  ?  How  is  coke 
made  ?     What  is  breeze  ? 


II. 

Concrete,  Mortar. 

Things  to  be  Seen. — Flint — sand — pebbles — limestone — 
qui eli-lime — slaked  lime — chalk — marble — the  slaking 
of  lime — the  mixing  of  mortar. 

§  3.  Concrete. — In  order  to  get  a  firm  place  for  a 
house  to  stand  on,  the  mould  and.  earth  are  dug  away 
where  the  walls  are  to  be,  and  into  the  ditches  or 
trenches  so  formed  some  concrete  is  put.  This  concrete  is 
made  of  sand,  pebbles,  lime,  and  water.  The  sand  used 
is  found  upon  the  sea-shore  and  in  river-beds,  or  forming 
layers  (sometimes  hundreds  of  feet  thick)  in  the  earth. 
It  has  been  formed  by  the  breaking  of  flints  or  the 
crumbling  to  pieces  of  granite  and  some  other  rocks. 
Sand  and  gravel  and  many  pebbles  are  often  little  else 
than  grains  or  lumps  of  silica,  which  is  a  body  containing 
two  elements  (see  §  29).  Pebbles  used  for  concrete 
differ  from  grains  of  sand  only  in  their  larger  size.  The 
lime  has  to  be  made ;  and  it  can  be  made  either  out  of 
chalk,  or  marble,  or  other  kind  of  limestone.  These 
three  things  are  little  else  but  lime  united  with  a  gas 
called  carbonic  acid  (see  §§  8,  30,  31,  32).  Whole 
mountains  are  made  of  such  kinds  of  limestone.  The 
way  lime  is  made  out  of  limestone  is  as  follows : — A 
hollow  tower  of  stone  or  bricks,  called  a  lime-kiln,  is 
built,  having  a  small  hole  at  the  bottom,  and  being  open 
at  the  top.  A  coal-fire  is  lighted  at  the  bottom,  and 
lumps  of  limestone  and  coal  are  thrown  in  from  the  top. 


12  MORTAR,  BRICKS. 

The  coal  burns  away,  and  the  heat  which  it  gives  drives 
the  gas  (carbonic  acid)  out  of  the  limestone,  and  leaves 
lumps  of  lime  called  quick-lime.  When  about  its  own 
weight  of  water  is  poured  upon  quick-lime,  the  lime  swells 
up,  gets  very  hot,  and  falls  to  pieces  as  a  white  powder 
called  slaked  lime.  To  make  the  concrete,  eight  parts  by 
weight  of  pebbles,  four  of  sand,  and  one  of  quick-lime  are 
mixed  together  with  water  so  as  to  form  a  thick  pasty 
mass.  When  this  is  put  into  the  trenches,  it  gets  after  a 
time  as  hard  as  stone,  and  makes  a  firm,  smooth,  dry 
place  for  the  bricks  of  the  wall  to  rest  on. 

§  4.  Mortar. — Mortar  is  made  in  the  same  way  as 
concrete,  only  no  pebbles  are  used.  The  best  sand  to 
use  is  river-sand ;  and  if  sea-sand  is  used,  it  should  be 
washed  in  fresh  water  to  get  rid  of  the  sea-salt  which  is 
in  it. 

Questions. — "What  is  concrete  made  of?  Where  is  sand  found? 
What  has  sand  been  made  from  ?  What  are  pebbles  ?  What  is 
limestone  ?  How  is  quick-lime  made?  How  is  slaked  lime  made 
from  quick-lime  ?  What  happens  when  water  is  poured  on  quick- 
lime ?     How  is  mortar  made  ? 


III. 

Bricks,  Clay,  Tiles,  Chimney-pots,  Drain-pipes. 

Things  to  be  Seen. — Some  dry  and  ivet  clay — a  brick — 
■pieces  of  earthenware. 

§  5.  Bricks. — Bricks  are  made  of  Clay.  Pure  clay  is 
white ;  but  the  clay  of  which  common  bricks  are  made 
is  brown,  yellow,  grey,  or  red,  and  sometimes  bluish  or 
nearly  black.  These  colours  are  usually  caused  by  iron 
rust.  When  rocks  are  exposed  to  the  weather — that  is, 
to  air,  and  rain,  and  frost  (see  §  33),  and  sunshine — ■ 
they  gradually  crumble  to  pieces,  and  are  carried  down 
by  brooks  into  rivers,  and  by  rivers  into  lakes  or  the 
sea.  Some  parts  of  the  rocks  are,  indeed,  quite  dissolved, 
just  as  salt  is  dissolved  by  water  (see  §  116).     Others 


BRICKS.  1 3 

are  ground  by  being  rubbed  together  in  the  rivers  to  the 
fineness  of  grains  of  mud,  others  to  sand,  others  to  gravel 
or  pebbles.  When  the  river  enters  the  lake  or  the  sea, 
the  largest  pieces  of  solid  settle  down  soonest,  and  so  rest 
near  the  river's  mouth,  while  the  finest  settle  last,  and  so 
are  carried  furthest.  The  clay  which  forms  part  of  many 
rocks  is  broken  into  very  line  particles  indeed,  and  so  it 
is  carried  out  a  long  way,  and  is  separated  from  the 
gravel  and  sand.  Clay  is  thus  formed  at  the  bottoms  of 
lakes  and  seas.  And  wherever  clay  is  found,  that  place 
must  at  one  time,  ages  and  ages  ago,  have  been  at  the 
bottom  of  water,  although  now  it  may  be  far  above  the 
sea-level.  Some  clay  is  moist ;  some  is  so  dry  and  hard, 
that  it  has  to  be  ground  with  water  before  it  can  be  used 
for  brick-making.  To  make  bricks,  the  clay  which  has 
been  dug  up  is  broken  and  exposed  to  the  air  and  frost 
through  the  winter  months.  It  is  then  worked  or 
kneaded  with  enough  water  to  make  it  very  stiff,  and  all 
pebbles  are  carefully  picked  out.  Then  the  brick-maker 
takes  a  mould,  which  is  a  wooden  or  iron  box  of  the 
shape  of  the  brick,  having  neither  top  nor  bottom,  lie 
strews  some  sand  on  a  board,  and 'having  wetted  the 
inside  of  the  mould,  strews  some  sand  on  it  also.  This 
prevents  the  clay  sticking  to  the  mould.  He  then  puts 
the  mould  upon  the  board,  and  fills  it  with  clay  higher 
than  the  edge  of  the  mould.  The  top  is  then  smoothed 
off  by  a  stick,  and  the  mould  and  brick  taken  away  to  a 
flat  floor.  The  raw  brick  is  taken  out  of  the  mould  and 
placed  flat  on  the  floor,  where  it  rests  till  it  gets  dry 
enough  to  bear  handling  without  injury.  The  raw  bricks, 
when  thus  partly  dry,  are  trimmed  with  a  knife,  anil 
piled  on  one  another  in  low  walls,  in  such  a  way  that 
there  are  spaces  between  them  for  the  air  to  go  round. 
The  tops  of  such  walls  are  sometimes  covered  with  straw, 
or  otherwise  roofed,  to  keep  off  the  rain.  After  being 
thus  further  dried,  the  raw  bricks  are  ready  for  burning. 
There  are  two  ways  of  burning  bricks  :  they  are  burnt 


14  TILES,  CHIMNEY-POTS,  DRAIN-PIPES,  SLATE. 

either  in  Kilns  or  Clamps.  A  Kiln  is  a  brick  house 
nearly  square,  and  about  as  high  as  it  is  wide.  Inside 
are  arched  brick  floors,  with  holes  in  them,  and  the  raw 
bricks  being  put  upon  these  floors,  some  fuel  which 
blazes  is  put  in  at  a  hole  at  the  bottom  of  one  of  the 
walls,  so  th  d  the  flame  playing  amongst  the  bricks  bakes 
them.  The  Clamp,  which  is  more  often  used,  and  is 
often  called  a  kiln,  is  built  of  the  raw  bricks  themselves. 
A  layer  of  these  being  laid  on  the  earth,  a  mixture  of 
small  coal,  breeze,  and  cinders  is  strewn  upon  them,  then 
another  layer  of  bricks  a  little  way  apart,  then  more  fuel, 
and  so  on.  In  building  the  clamp,  hollow  spaces  are 
left,  which  serve  as  chimneys ;  and  b}'  closing  the  outer 
ends  of  one  or  other  of  these,  the  draught  can  be  regu- 
lated. This  regulation  of  the  draught  is  also  done  by 
plastering  wet  clay  at  various  places  on  the  outside,  so  as 
to  stop  the  draught  there ;  for  where  there  is  no  air  the 
fire  is  smothered.  When  the  fuel  is  burnt  out  and  the 
clamp  is  cool,  the  bricks  are  taken  out,  and  are  now  found 
to  be  full  of  small  holes,  hard,  and  not  to  be  softened  by 
water.  They  are  also  found  to  have  shrunk  in  size. 
The  holes  in  the  bricks  let  the  soft  mortar  enter  them  a 
little  way,  so  that  when  the  mortar  sets,  or  hardens,  the 
bricks  are  not  only  stuck  but  clamped  together. 

§  6.  Tiles,  Chimney-pots,  and  Drain-pipes. — 
These  are  also  made  of  clay.  The  clay  must  be  purer 
than  that  which  may  be  used  for  common  bricks,  and  the 
stones  more  carefully  taken  out.  Sand  is  often  mixed 
with  the  clay.  To  make  glazed  tiles  or  drain-pipes, 
which  have  to  be  waterproof,  common  salt  is  heated  in 
the  kiln  along  with  the  tiles  or  drain-pipes.  Crockery 
of  all  kinds  is  also  made  with  clay  (see  §  84). 

§  7.  Slate. — When  clay  has  been  in  a  dry  state  for  a 
very  long  time,  and  has  been  pressed  very  much  by  other 
rocks,  it  can  no  longer  be  softened  by  water,  and  it  can, 
when  taken  freshly  from  the  quarry,  be  split  in  flakes 
or  sheets  by  a  chisel.     It  is  called  Slate.     Some  time 


LIMESTONE,  MARBLE,  SANDSTONE.  15 

after  being  taken  from  the  quarry,  especially  if  the  slate 
is  acted  on  by  frosts  and  thaws,  it  can  no  longer  he  split. 
Slate  is  used  in  buildings  for  covering  roofs,  for  cisterns, 
and  sometimes  for  mantelpieces. 

Questions. — What  is  meant  by  the  weather  ?  What  happens  to 
roeks  when  they  are  acted  on  by  the  weather?  How  has  elay  been 
made?  In  brick-making,  what  is  done  to  the  clay  to  make  it  lit 
for  bricks?  How  are  bricks  made  of  the  right  shape?  How  is 
tlie  clay  stopped  from  sticking  to  the  mould?  How  are  bricks 
dried?  What  is  a  brick  kiln?  What  is  a  brick, clamp?  What 
kind  of  fuel  is  used  in  a  kiln?  What  fuel  is  used  in  a  clamp? 
How  is  the  heating-  in  a  clamp  regulated  ?  How  does  a  baked 
brick  differ  from  a  dry  one  ?  What  is  the  use  of  the  holes  in  the 
brick  ?  How  does  clay  used  for  tiles,  chimney-pots,  and  drain- 
pipes differ  from  brick  clay  ?  How  are  such  things  glazed  ?  What 
is  slate  ?     What  is  it  used  for? 


IV. 

Limestone,  Marble,  Sandstone,  Granite, 
Plaster,  Thatch,  Shingles. 

Things  to  be  Seen.  —  Pieces  of  limestone — marble — 
sandstone — granite — dry  plaster  of  Paris — the  setting 
of  pi 'aster  of  Paris  when  mixed  xoith  icater. 

§  8.  Limestone. — Some  very  small  animals  which  live 
in  the  sea  take  the  carbonate  of  lime  from  the  sea,  and  use 
it  to  make  their  shells  or  skeletons.  When  such  animals 
die,  the  carbonate  of  lime  which  they  had  gathered  settles 
to  the  bottom  of  the  sea,  and  makes  in  time  beds,  which 
may  be  hundreds  of  feet  thick.  This  slowly  hardens,  and 
is  then  called  limestone.  If  this  sea-bottom  rises  above 
the  general  level  of  the  sea,  the  sea  drains  away  from  it, 
and  the  limestone  is  then,  of  course,  found  inland,  away 
from  the  sea,  just  as  coal  is  so  found  (see  §  1). 

§  9.  Marble. — When  limestone  is  acted  on  by  water, 
and  more  of  the  same  gas  as  it  already  has  (carbonic  acid), 
it  becomes  hard  enough  to  be  polished.  It  iff  then  called 
marble. 

§  10.   Sandstone. — When  beds  of  sand  become  wetted 


]  6  GRANITE,  PLASTER   OR   GYPSUM,  THATCH. 

through  with  water  containing  silica  (see  §  3),  a  hardening 
takes  place,  much  like  the  hardening  of  mortar,  and  the 
loose  sand  is  changed  into  sandstone. 

§11.  Granite. — Granite  is  a  rock  which  seems  to  have 
once  been  melted,  and  to  have  cooled  slowly  far  under- 
ground, and  while  it  was  much  squeezed.  Granite  is  a 
mixture  of  several  different  things.  There  are  little  black 
or  white  glittering  scales  in  it,  called  mica.  Then  there 
are  transparent  crystals — that  is,  crystals  easily  seen 
through — called  quartz,  and  larger  milky-white  or  pink 
crystals,  called  felspar.  In  some  kinds  of  granite  one  can 
see  crystals  of  felspar  an  inch  or  two  long. 

§  12.  Plaster  or  Gypsum. — Plaster  is  found  in  the 
earth  as  a  rock.  A  fifth  of  its  weight  is  water.  When 
the  gypsum  is  heated  in  a  kiln,  not  too  strongly,  it  gives 
off  this  water,  and  becomes  so  soft  that  it  can  easily  be 
crumbled  and  ground  to  a  fine  powder.  When  so  dried 
and  ground,  it  is  called  plaster  of  Paris.  When  this 
plaster  of  Paris  is  mixed  with  even  so  much  water  as  to 
make  a  very  thin  cream,  it  becomes' hot  and  dry,  just  as 
quickdime  does.  It  becomes  hard,  and  because  its  surface 
when  dry  is  smooth,  it  is  used  for  taking  casts.  The 
mouldings  on  the  cornices  of  rooms  and  the  ornaments  of 
ceilings  are  casts  made  of  plaster  of  Paris.  The  ceilings 
of  rooms  are  made  of  plaster,  or  plaster  and  mortar,  with 
which  are  mixed  the  hairs  of  cows  and  oxen,  which  hairs 
are  scraped  from  the  hides  when  hides  are  tanned.  The 
hair  makes  the  plaster  less  crumbly  ;  it  binds  the  brittle 
plaster  together  (see  §  97). 

§  13.  Thatch. — The  roofs  of  houses  are  often  made  of 
straw  or  of  rushes.  Straw  does  not  last  very  long,  but  a 
roof  of  rushes  may  last  twenty  or  thirty  years.  The  rush 
is  laid  on  thickly,  and  bound  to  the  open  woodwork  of 
the  roof  ;  then  more  is  bound  to  that,  and  so  on.  Thatched 
roofs,  like  houses  built  entirely  of  wood,  are  dangerous  to 
neighbouring  houses  if  they  catch  fire,  and  they  themselves 
are  in  threat  danger  from  neighbouring  fires.     So  wooden 


SHINGLES,  METALS    IN    GENERAL.  17 

houses  and  thatched  houses  are  not  allowed  to  he  huilt 
in  towns ;  hut  in  the  country,  where  straw  or  rushes  are 
plentiful,  or  slate  scarce,  thatched  roofs  are  made,  and, 
being  thick,  they  keep  the  heat  in  in  winter,  and  the  heat 
out  in  summer. 

§14.  Shingles. — Sometimes  (hut  in  this  country  not 
often)  the  roots  of  houses  are  made  of  little  hoards  the 
size  and  shape  of  tiles.  These  are  nailed  to  the  frame  of 
the  roof  in  such  a  way  that  they  overlap  one  another. 
Such  wooden  tiles  are  called  shingles. 

Questions. — What  is  limestone  made  of?  What  is  it  made  by? 
What  is  it  made  from  ?  How  is  it  that  limestone  is  found  far  from 
the  sea  ?  What  is  marble  ?  How  has  sandstone  been  made  ?  How 
has  granite  been  made  ?  What  is  it  made  of  ?  Where  is  gypsum 
found  ?  What  is  the  difference  between  gypsum  and  plaster  of 
Paris?  How  is  plaster  of  Paris  made  from  gypsum?  What  hap- 
pens when  plaster  of  Paris  is  mixed  with  water  ?  What  is  plaster 
of  Paris  used  for?  Why  is  hatr'rnixgd  with  plaster?  What  is 
thatch  made  of  ?  Why  is  it  not  used  in  towns  ?  What  is  the  good 
of  thatch  ?     What  is  the  harm  of  it  ?     What  are  shingles  ?. 


V. 

Metals  in  General,  Iron,  Slag. 

Things  to  be  Seen. — Pieces   of  iron   ore — limestone — 
coke — slag — cast-iron — wrougltt-iron. 

§  15.  Metals  in  General. — There  are  four  metals 
chiefly,  used  in  building  a  house — Iron,  Lead,  Copper, 
and  Zinc.  Iron  is  used  where  great  strength  is  wanted  ; 
it  is  cheap.  Lead  is  used  where  its  softness  is  of  advan- 
tage, as  when  one  wants  to  cover  wood  from  the  rain. 
The  lead  can  be  easily  bent  into  any  shape ;  it  does  not 
rust  away,  like  iron.  Zinc  is  dearer  than  either  lead  or 
iron.  It  is  harder  than  lead,  but  softer  than  iron  ;  and  it 
has  this  advantage  over  lead,  that  its  rust  is  not  very 
poisonous,  while  the  rust  of  lead  is  very  poisonous.  Zinc 
does  not  rust  away,  like  iron,  though  it  tarnishes  on  the 
surface,  even  in  the  purest  damp  air.     In  places  where 

B 


18  IRON. 

coal  is  burnt,  the  zinc  is  eaten  away  because  the  air  of  such 
places  is  acid.  Copper  is  dear,  and  its  rust  is  poisonous, 
but  is  easily  cleaned.  Of  these  four  metals,  copper  is  the 
only  one  which  is  even  sometimes  found  in  nature  in  the 
.  pure  state— that  is,  as  a  metal.  All  the  three  others,  and 
copper  generally,  have  to  be  got  from  minerals,  which  are 
found  in  different  places,  generally  in  the  rocks  beneath 
the  surface  of  the  earth.  These  minerals  are  called  ores, 
and  most  of  them  have  special  names,  for  there  are  several 
ores  of  each  metal.  A  metal  exists  in  its  ore  something 
in  the  same  way  as  salt  exists  in  the  sea.  An  ore  of  a 
metal  is  that  metal  united  with  something  else  ;  and,  to 
get  the  metal  by  itself,  that  something  has  to  be  taken 
away.  To  get  salt  from  the  sea,  one  has  only  to  heat  the 
salt-water,  and  boil  away  the  water.  From  some  ores  the 
pure  metal  may  be  got  in  the  same  way  ;  from  others  the 
metal  can  only  he  got  by  mixing,  and  in  many  cases  heating, 
the  ore  with  something  which  takes  away  the  substance 
other  than  the  metal  which  is  in  the  ore.  It  follows,  of 
course,  that  the  weight  of  thjs  metal  got  from  an  ore  i3 
less  than  the  weight  of  the  ore. 

§  16.  Iron. — The  nails  and  screws  which  are  used  to 
fasten  the  wooden  parts  of  a  house  together  are  made  of 
item,  and  iron  is  got  as  follows  : — There  are  found  in  the 
earth  layers  or  seams  of  substances,  called  iron-ore.  These 
contain  iron-rust,  and  sometimes  the  gas  carbonic  acid, 
and  sometimes  clay.  In  order  to  get  the  metal-iron  out 
of  this  mixture,  the  ore  is  mixed  with  limestone  and  coke 
(see  §  2)  or  charcoal  (see  §  30),  and  put  into  a  hollow 
brick  tower,  something  like  a  lime-kiln,  only  much  larger. 
A  little  way  above  the  bottom  of  this  tower,  which  is 
called  a  furnace,  there  is  a  hole  through  the  wall,  called 
the  blast-hole.  The  coke  at  the  bottom  is  set  tire  to,  and 
air  is  blown  in  through  the  hole  to  quicken  the  burning. 
The  lime  and  the  coke  together  take  nearly  everything 
away  from  the  iron,  and  leave  it  as  a  melted  metal,  which, 
being  heavy,  makes  its  way  down  to  the  bottom  of  the 


IRON.  1  J 

furnace  below  the  hole.  Some  of  the  things  which  were 
united  with  the  iron  now  unite  with  the  coke,  and  rise 
and  escape  from  the  top  of  the  tower  as  a  gas  ;  the  others 
form,  with  the  lime  and  ashes  of  the  coke,  a  body  which, 
at  this  high  temperature,  melts,  and  also  sinks  down  and 
settles  upon  the  melted  iron.  It  is  called  Slag,  and  is 
like  melted  glass  ;  in  fact,  it  is  a  kind  of  glass.  If  a  hole 
is  opened  in  the  furnace  lower  than  the  blast-hole  near  the 
bottom  of  the  furnace,  the  iron  runs  out ;  if  another  hole 
is  opened  above  the  iron,  the  slag  runs  out.  As  the  coke 
itself  burns  away,  and  the  slag  and  the  metal  are  run  off, 
the  upper  parts  of  the  mixture  of  coke,  limestone,  and  ore 
sink  slowly  down.  The  furnace  would  thus  become 
empty.  Instead  of  allowing  this,  fresh  quantities  of  the 
same  mixture  are  continually  put  in  at  the  top,  so  that  the 
same  furnace  is  kept  alight  for  many  years.  The  iron 
which  is  thus  made  is  called  Cast-iron  ;  it  can  be  melted, 
though  not  so  easily  as  lead  or  tin,  and  it  can,  in  the  melted 
state,  be  cast  in  moulds  made  of  dry  sand,  so  as  to  have 
any  form.  In  many  houses  and  bridges,  railway  stations, 
and  so  on,  beams  and  arches  of  cast-iron  are  used.  Cast- 
iron  is  very  brittle.  It  is  not  pure  iron.  It  contains  a 
considerable  quantity  of  carbon,  and  this  makes  it  brittle. 
To  get  it  pure,  it  is,  when  it  is  melted,  stirred  up  while  a 
draught  of  very  hot  air  is  blown  over  it  ;  then  it  is  ham- 
mered, and  squeezed,  and  kneaded  like  dough.  By  this 
means  some  of  its  impurities  are  squeezed  out  and  others 
are  burnt  off.  That  which  is  burnt  off  is  mainly  carbon. 
The  iron  thus  purified  is  called  Wrought-iron.  It  is 
much  more  tough  than  the  cast-iron— that  is,  it  can  be 
bent,  and  remain  bent,  without  breaking ;  but  it  is  not  so 
easy  to  melt.  It  can  be  rolled,  when  hot,  into  bars  and 
rods,  and  rolled  between  rollers  into  sheets  or  plates.  It 
is  so  tough  that,  when  cold,  it  can  be  drawn  through  little 
holes,  and  so  made  into  wire.  It  can  be  pressed  or 
stamped  into  nails  and  cut  into  screws. 
Steel  will  be  described  in  §  80. 


20  LEAD,  ZINO. 

Questions. — What  are  the  chief  metals  used  in  building  ?  "What 
is  each  used  for,  and  why  ?  What  is  au  ore,  and  where  are  ores 
found  ?  Why  is  the  weight  of  metal  which  can  he  got  from  an 
ore  always  less  than  the  weight  of  the  ore  itself?  What  is  iron  ore 
generally  made  ot  ?  How  is  an  iron  furnace  made  ?  What  is  put 
in  at  the  top  ?  What  is  the  use  of  the  fuel  ?  What  is  the  use  of 
the  lime  ?  What  is  slag  ?  How  is  cast-iron  made  into  wrought- 
iron  ?  What  is  the  difference  between  them — (1)  as  to  what  they 
are  made  of,  (2)  as  to  what  they  are  like,  (3)  as  to  what  they  are 
used  for  ? 


VI 
Lead,  Zinc,  Copper,  Brass,  Tin,  Mercury,  Tin- 
plate,  Zinc-plate,  Galvanised  Iron. 

Things  to  be  Seen. — Pieces  of  the  metals — lead,  zinc,  cop- 
per, brass,  tin,  and  mercury.  Also,  ores  of  these 
metals,  such  as  sulphides  of  lead,  zinc,  and  copper — 
oxide  of  tin — cinnabar — sal-ammoniac — some  tin- 
plate — some  zincplate. 

§  17.  Lead. — Lead  is  used  in  houses  chiefly  for  water- 
pipes  and  cisterns,  and  for  lining  the  gutters  or  roofs,  and 
sometimes  for  covering  roofs  Though  clean  bright  lead 
easily  tarnishes  in  the  air — that  is,  rusts — the  rust  does 
not  go  very  deep,  and  that  which  forms  on  the  surface 
shields  the  metal  beneath. 

Lead  is  found  in  the  earth  united  with  different  sub- 
stances. The  chief  ores  of  lead  are  two.  The  most  com- 
mon one  of  these  is  a  union  of  lead  with  sulphur — that  is, 
brimstone.  This  ore  gives  up  its  lead,  when  heated,  as 
follows  : — It  is  first  heated  red-hot  and  stirred  about,  whiie 
it  is  exposed  to  plenty  of  air — that  is,  it  is  roasted.  It  is 
then  heated  more  strongly,  with  only  enough  air  to  burn 
the  fuel.  All  the  sulphur  is  burnt  ( ff ,  and  the  melted 
lead  remains  ;  or  the  roasted  ore  may  be  heated  with  scraps 
of  wrought-iron,  which  takes  away  everything  else,  leaving 
the  lead. 

§  18.  Zinc  (also  called  Spelter). — The  chief  ores  of 


COPPER,  BRASS,  TIN.  21 

zinc  are  (1)  the  rust  of  zinc  united  with  carbonic  acid, 
and  (2)  zinc  united  with  sulphur.  To  get  zinc  from  llio 
first,  it  is  first  heated  in  a  kiln  (not  a  clamp)  like  a  brick- 
kiln ;  this  drives  off  the  carbonic  acid,  and  leaves  zinc- 
rust.  The  next  process  is  to  mix  the  zinc-rust  with  fine 
coal-powder  and  a  little  water,  and  to  heat  it  white-hot  in 
wide  earthen  tubes,  closed  all  round  except  at  one  end, 
where  narrower  open  tubes  are  fastened  on.  The  zinc- 
i'ust  is  changed  into  zinc,  because  the  coal  takes  away  that 
with  which  it  is  united.  To  get  zinc  from  the  ore  which 
contains  sulphur,  the  ore  is  first  roasted — that  is,  it  is 
heated  in  an  open  furnace  by  means  of  a  flame  playing 
upon  it.  By  this  means  the  zinc-sulphur  is  changed  to 
zinc-rust,  and  the  latter  is  mixed  with  coal  and  heated  as 
above. 

§  19.  Copper. — Copper  is  sometimes,  but  rarely,  found 
as  a  metal.  It  is  also  found  united  with  sulphur,  with 
sulphur  and  iron,  as  copper-rust,  and  as  copper-rust 
united  with  carbonic  acid.  The  process  of  getting  pure 
copper  from  its  ores  is  a  long  and  difficult  one.  If  the 
sulphur  copper-ore  is  worked  for  copper,  it  is  first  roasted ; 
this  changes  the  copper-sulphur  into  copper-rust.  This  is 
then  melted  and  broken  up,  and  again  roasted,  and  so  on 
several  times.  At  last  the  copper-rust  is  heated  with  fine 
coal ;  this  brings  it  to  the  state  of  crude  copper.  It  is 
again  and  again  broken  up  (by  being  poured  into  water 
when  melted),  and  roasted  and  melted.  At  last,  when  it 
is  nearly  pure,  it  is  covered,  when  melted,  with  charcoal, 
to  keep  out  the  air,  and  stirred  up  with  a  wooden  pole. 
This  finally  purifies  it  by  converting  any  copper-rust  in  it 
into  copper. 

§  20.  Brass. — Brass  is  a  mixture  of  copper  and  zinc. 
The  two  mix  when  melted  together,  and  any  weight  oi 
copper  will  mix  with  any  weight  of  zinc.  fSo  that  a  brass 
may  be  rich  in  copper  and  poor  in  zinc,  or  the  other  way 
about. 

§21.  Tin. — The  ore  of  tin  which  is  most  useful  and 


22  MERCURY,  OR   QUICKSILVER;    TIN-PLATE. 

abundant  is  tin-stone,  which  is  rust  of  tin.  This  is 
crushed  and  washed,  so  as  to  get  rid  of  lighter  grains, 
which  contain  no  tin,  hut  sometimes  other  metals.  The 
ore  is  then  roasted,  like  the  copper-ore,  by  means  of  which 
any  sulphur  which  may  be  there  is  driven  off.  The  ore  so 
purified  is  then  mixed  with  small  coal  and  some  slaked 
lime  (see  §  3),  and  strongly  heated.  The  slaked  lime 
takes  up  sand,  and  forms  a  slag,  and  at  the  same  time 
gives  up  bubbles  of  steam,  and  so  stirs  up  the  tin.  The 
coal  unrusts  the  tin-rust,  and  leaves  the  metal  itself.  This 
is  still  impure.  To  purify  it  partly,  it  is  slowly  heated, 
and  the  tin,  melting,  first  runs  off,  and  is  collected.  To 
get  it  still  purer,  it  is  re-melted,  and  blocks  of  green 
wood  are  thrust  beneath  its  surface.  The  heat  of 
the  melted  metal  causes  the  water  in  the  wood  to 
boil,  and  this  thoroughly  stirs  up  the  tin,  and 
brings  to  the  surface  a  scum,  which  contains  most  of  the 
impurities. 

§  22.  Mercury,  or  Quicksilver. — This  metal  is  a 
liquid  at  the  ordinary  temperature  of  the  air.  It  is  some- 
times found  in  the  metallic  state  as  small  drops  in  the 
place  where  mercury  ores  occur.  The  principal  ore  of  mer- 
cury is  Cinnabar,  which  is  mercury  united  with  sulphur. 
This  ore  is  ground  to  powder,  and  mixed  with  quick-lime. 
The  mixture  is  put  into  a  long  iron  box,  in  one  end  of 
wdiich  is  an  iron  tube,  bent  down,  and  dipping  under 
water.  When  the  ore  is  thus  heated  with  the  lime,  the 
latter  takes  away  the  sulphur  from  the  mercury,  and 
leaves  it  as  a  metal.  But  at  this  temperature  the  mercury 
boils  away  as  a  gas,  and  the  mercury  gas  meets  with  the 
water,  and  is  so  cooled  that  it  becomes  liquid — just  as 
the  steam  from  a  kettle  becomes  water  when  it  touches 
a  cold  plate  held  near  the  spout.  The  mercury  drops 
through  the  water  as  a  liquid  metal.  Very  often  the 
mercury  is  got  by  heating  the  cinnabar  by  itself,  without 
lime. 

§  23.  Tin-plate. — Sheet-iron  covered  with  tin  is  shielded 


ZIN'C-rLATF,  OR    GALVANISED    IRON.  23 

by  the  tin  from  the  rusting  action  of  air  and  water;  so 
that,  although  tinned  iron  is  dearer  in  the  iirst  place  than 
simple  iron,  it  lasts  longer,  and  may  be  cheaper  in  the  end. 
Tinned  iron,  or,  as  it  is  sometimes  called,  "  tin-plate,"  is 
used  for  roofing  instead  of  tiles,  and  for  such  pots  and 
pans  used  in  cooking  as  are  not  heated  hotter  than  boiling 
water,  such  as  kettles  or  stew-pans.  Grid-irons,  frying- 
pans,  and  pie-dishes  are  heated  so  hot  that  the  tin  would 
melt — for  tin  melts  rather  easily.  Iron-plate— that  is, 
sheet-iron — is  covered  with  tin  in  the  following  way  :— 
The  sheets  of  iron  are  first  thoroughly  cleaned  by  being 
rubbed  with  dilute  oil  of  vitriol  (see  §  132),  sand,  and 
water ;  then  quickly  wiped  and  plunged  into  hot  melted 
fat.  This  boils  away  the  dampness  on  them.  They  are 
then  dipped  in  a  pan  of  melted  tin  covered  with  melted 
fat ;  the  tin  sticks  to  the  iron.  When  they  are  taken  out 
of  the  tin  bath,  they  are  put  into  another  grease  bath, 
where  the  unnecessary  tin  drains  off,  and  then  they  are 
cooled  gradually. 

§  24.  Zinc-plate,  or  Galvanised  Iron. — There  are 
several  ways  by  which  iron  is  coated  with  zinc.  The 
simplest  plan  is  to  dip  the  perfectly  clean  iron  plate  into 
melted  zinc,  the  surface  of  which  is  covered  with 
Sal-ammoniac.  Sal-ammoniac  is  a  body  got  from 
the  gasworks  (see  §  40)  by  adding  hydrochloric  acid 
(see  §  120)  to  the  water  which  has  dissolved  the 
ammonia.  Sal-ammoniac  is  made  of  nitrogen,  hydrogen, 
and  chlorine. 

Questions. — What  is  lead  used  for  in  houses,  and  why  ?  What 
is  the  commonest  ore  of  lead  ?  How  is  lead  got  from  its  ore  ? 
What  are  the  two  chief  ores  of  zinc  ?  How  is  the  metal  got  from 
each  of  them  ?  What  are  the  chief  ores  of  copper?  What  is  the 
use  of  roasting  sulphur-copper  ore  ?  What  is  done  to  the  roasted 
copper  ore,  and  why  ?  What  is  brass  ?  What  is  tin-stone  ?•  What 
is  the  use  of  roasting  the  tin-stone  ?  What  is  then  done  with  the 
roasted  ore?  Why?  What  is  the  chief  ore  of  mercury?  How 
is  mercury  got  from  it  ?  What  is  tin-plate  ?  What  is  it  used  for  ? 
How  is  sheet-iron  covered  with  tin  ?  What  is  zinc-plate  ?  What 
is  sal-ammoniac  ?     Where  is  it  got  from,  and  how  i 


24  GLUE, 

VII. 

Glue,  Whitewash,  Glass,  Litharge,  Putty. 

Things  to  be  Seen. — Glue — glue  softened  in  cold  water — : 
weak  solution  of  glue — the  same  after  setting — chalk — 
whiting — pieces  of  different  kinds  of  glass — emery 
powder — iron  rust  (rouge) — oxide  of  tin  (that  is, 
"putty  powder"  ) — litharge — linseed  oil. 

§  25.  Glue. — The  skins,  horns,  hoofs,  or  sinews  of 
animals  are  stirred  about  for  several  weeks  in  water  to 
which  has  been  added  enough  slaked  lime  (see  §  3)  to 
form  a  milky  liquid.  They  are  then  taken  out  and 
exposed  to  the  air  by  being  frequently  turned  over,  and 
are  left  to  dry;  they  are  then  washed  and  boiled  with 
water.  The  liquid  thus  got  is  filtered  through  flannel 
and  poured  into  boxes  or  barrels,  where  it  becomes  a  jelly 
called  Size.  The  jelly  is  turned  out  upon  a  table  and  cut 
into  slices  by  a  wire,  and  again,  downwards,  b}^  a  knife. 
The  slices  of  jelly  are  placed  on  nets,  which  are  hung  in 
a  dry  room.  The  water  passes  off  and  leaves  cakes  of 
glue,  which  can  be  kept  for  any  length  of  time.  To  use 
glue,'  it  has  to  be  broken  into  little  pieces  and  covered 
with  cold  water  till  it  is  quite  soft.  The  pot  which  holds 
it  is  then  put  into  another  pot  in  which  there  is  some 
water,  and  the  outer  water  is  boiled.  This  prevents  the 
glue  from  being  burnt,  which  would  happen  if  the  inner 
pot  were  put  over  the  flame.  To  stick  things  together 
with  glue,  the  two  things  are  covered  with  glue,  and  kept 
pressed  together  till  the  glue  has  cooled  and  become  a 
jelly,  and  further,  till  the  water  in  it  has  escaped  into  the 
air,  leaving  nothing  but  solid  glue  between  the  things. 
A  mixture  of  plaster  of  Paris  and  glue  makes,  when  cold 
and  dry,  a  very  hard  cement,  and  is  useful  to  fill  up  holes 
in  wood,  such  as  the  holes  where  screws  and  nails  have 
been;  but  such  a  cement  will  not  stand  water,  which 
softens  the  glue,  and  gradually  dissolves  the  plaster  of 
Paris. 


WHITEWASH^  GLASS.  25 

§  26.  Whitewash.— Whiting  is  very  fine-grained 
Chalk,  which  has  heen  cleaned.  Chalk  is  formed  much 
in  the  same  way  as  limestone  (see  §^  3,  8)  :  it  is 
softer  and  generally  whiter  than  limestone.  Whiting 
is  made  from  chalk  as  follows  : — The  chalk  is  ground 
with  water  into  a  paste,  and  then  stirred  up  with 
water  and  allowed  partly  to  settle  :  the  particles  of  sand 
which  may  be  in  the  chalk,  and  the  larger  grains  of 
chalk,  settle  down  to  the  bottom  first ;  the  very  fine 
grains  of  chalk  remain  in  the  water,  making  it  milky. 
This  milky  water  is  put  into  a  vat,  and  allowed  to  stand 
for  a  long  time.  The  fine  chalk-grains  at  last  settle  down, 
leaving  the  water  clear.  The  clear  water  is  poured  away, 
and  the  soft  white  chalk-mud  is  drained  and  dried,  and  is 
then  called  whiting.  If  glue  (see  §  25)  is  dissolved  in  a 
large  quantity  of  hot  water  and  allowed  to  cool,  it  becomes 
a  jelly  called  "size;"  on  heating  the  size,  it  melts  again. 
Whitewash  is  made  of  melted  size  mixed  with  whiting. 
When  the  whitewash  dries  (that  is,  when  the  water  escapes 
into  the  air),  there  is  nothing  left  but  grains  of  whiting 
(fine  chalk)  stuck  together  by  glue ;  and  the  glue  sticks 
itself  and  the  whiting  to  the  thing  which  is  whitewashed. 

§  27.  Glass. — There  are  five  or  six  kinds  of  glass, 
which  differ  from  one  another  not  only  in  the  uses  to 
which  they  are  put,  but  also  in  the  things  of  which  they 
are  made,  and  the  ways  of  making  them.  The  glass  of 
which  common  windows  are  made  is  got  by  melting 
together,  in  an  earthenware  pot,  at  a  very  strong  heat, 
some  sand  and  soda  (see  §  120),  or  potashes,  or  both. 
For  crown  glass,  some  saltpetre  (see  §  50)  and  lime  (see 
§  3)  are  added.  For  plate  glass,  such  as  the  large  windows 
of  shops,  the  saltpetre  is  sometimes  left  out.  But  almost 
every  manufacturer  uses  these  things  in  different  propor- 
tions. To  give  the  glass  its  proper  shape  and  thickness 
for  windows,  an  iron  tube  is  put  into  the  pasty  melted 
glass,  and  the  lump  which  sticks  to  the  end  is  blown 
into  a  bubble,  like  a  soap-bubble.     The  place  opposite  to 


26  PUTTY. 

the  blowpipe  is  opened,  and  by  turning  the  blowpipe 
round — that  is,  by  trundling  it  like  a  mop — tbe  bole  opens, 
and  the  bubble  becomes  a  round  and  flat  sheet.  Instead 
of  this,  the  glass  bubble  is  often  blown  inside  a  wide  tube 
of  smooth  metal,  so  that  it  becomes  like  a  garden-roller  in 
shape;  then,  when  still  hot  and  soft,  it  is  cut  open  by  a 
straight  cut,  laid  open,  and  flattened  down.  To  make 
plate  glass,  the  pot  of  glass  is  emptied  on  a  metallic 
table,  and  rolled  out  like  a  pie-crust  by  a  metal  roller. 
It  is  then  put  in  an  oven  and  cooled  very  slowly,  because, 
if  it  is  cooled  quickly,  it  is  very  brittle.  Then  it  is 
ground  flat  with  sand  and  water,  smoothed  by  being 
ground  with  water  and  emery  (see  §  130)  of  increasing 
fineness,  and  then  polished  with  water  and  iron-rust ;  and 
the  polishing  is  finished  by  rubbing  two  plates  together, 
a  little  water  and  rust  of  tin  being  put  between  them. 
Crystal,  of  which  salt-cellars,  decanters,  and  "cut" 
glass  things  are  generally  made,  contains  lead-rust. 
•  §  28.  Putty. — To  fix  windows  in  their  frames,  putty  is 
generally  used.  This  is  made  by  grinding  and  kneading 
together  some  whiting  (see  §  26)  and  linseed  oil  (see  §  59), 
which  has  been  boiled  with  Litharge.  Litharge  is  a  rust 
of  lead — that  is,  an  oxide  of  lead.  The  boiling  of  the 
linseed  with  this  body  gives  the  oil  the  property  of  dry- 
ing ;  so  that  the  putty,  when  dry,  is  whiting  mixed  with 
the  hard  dried  oil.  When  not  in  use,  putty  may  be  kept 
soft  by  covering  it  with  water.  The  water  does  not  dis- 
solve it,  but  keeps  away  the  air,  which  would  otherwise 
dry  the  linseed  oil. 

Questions. — "What  is  glue  made  from  ?  How  is  it  made  ?  "What 
is  done  to  the  glue  when  it  is  wanted  to  he  used  for  sticking  things 
together  ?  How  does  the  glue  act  ?  What  is  whiting  ?  How  is  it 
made  from  chalk  ?  What  is  size  ?  What  is  common  window-glass 
made  from,  and  how  ?  What  is  crown  glass  ?  What  is  plate  glass  ? 
How  are  they  made  ?  What  is  crystal  (glass),  and  what  is  it  used 
for  ?  How  is  plate  glass  polished  ?  What  is  putty  used  for  ?  How 
is  it  made  ?  What  is  litharge  ?  What  is  the  use  of  hoiling  litharge 
with  linseed  oil  ?     Why  is  putty  kept  sometimes  under  water  ? 


PART     II. 


WHAT  MATTER  IS  MADE  OF. 
ELEMENTS,  AIE,    FIEE,    FLAME,   WATER 

VIII. 

Elements,  Air. 

Things  to  be  Seen. — Pieces  of  iron,  copper,  lead,  zinc, 
and  as  many  other  metals  as  can  be  easily  got — some 
water,  sand,  sugar,  and  glue — some  sulphur,  charcoal, 
charcoal  a  little  burnt,  shoioing  the  ash — a  thin  paper 
bag — a  bottle  of  soda  water. 

§  29.  Elements. — You  remember  that  there  are 
twenty-six  letters  in  the  alphabet,  and  that  every 
word  used  is  either  one  of  these  letters  alone  ("a"), 
or  is  made  by  uniting  two  or  more  letters  together. 
Think  of  the  number  of  words  which  there  are,  all  made 
of  these  twenty-six  letters.  Or  think  of  the  endless 
number  of  numbers  which  can  be  made  by  putting 
together  the  ten  numerals,  0,  1,  2,  and  so  on;  or  think  of 
the  number  of  tunes  which  can  be  played  with  twenty  or 
thirty  notes.  When  you  have  thought  of  this  well,  take 
up  any  piece  of  matter  you  please,  and  look  upon  it  as  a 
word.  If  it  be  a  piece  of  iron,  it  will  be  like  a  word  of 
one  letter.  If  it  be  a  drop  of  water,  or  a  grain  of  salt  or 
of  sand  (silica),  it  will  be  like  a  word  of  two  letters."  If 
it  be  a  lump  of  sugai',  it  will  be  like  a  word  of  three 
letters.  This  is  because,  just  as  all  words  are  made  of 
letters,  so  all  pieces  of  matter  are  made  of  Elements — 
that  is,  simple  single  kinds  of  matter,  which  can  no  more 


28  ELEMENTS,  AIR. 

be  divided  into  other  kinds  than  a  letter  can,  hut  which, 
like  the  letter  "  a,"  can  stand  by  themselves.  Iron  is  an 
element.  Water  is  made  of  two  elements.  So  is  salt ; 
but  the  elements  in  salt  are  neither  of  them  the  same  as 
either  of  the  elements  of  water.  Silica  is  also  made  of 
two  elements.  Sugar  is  made  of  three  elements,  glue  of 
four,  and  so  on. 

There  are  known  to  be  sixty-six  different  Elements. 
More  may  hereafter  be  found  in  nature.  Every  kind  of 
matter  which  can  be  got  at  has  been  examined,  and  has 
been  found  to  be  either  an  element  itself,  like  gold  or 
sulphur,  or  a  union  of  two  or  more  elements.  Elements 
are  the  letters  of  Matter. 

Not  only  has  every  known  thing  been  examined  in  this 
way,  and  been  proved  to  be  made  of  these  elements,  but, 
by  uniting  together  elements  and  compound  bodies  (that 
is,  bodies  themselves  made'up  of  elements),  a  very  great 
number  of  new  bodies  have  been  made  which  did  not 
before  exist,  just  as  new  words  may  be  formed  out  of  the 
known  letters.  But  while  new  words,  unless  they  de- 
scribe new  things, -are  nonsense,  there  is  no  nonsense  in 
nature,  nor  in  the  things  which  can  be  made  out  of 
matter. 

Many  of  these  elements  are  so  rare  that  we  seldom 
meet  with  them,  and  they  shall  not  be  talked  of  in  this 
book.  Others  are  so  common,  that  we  cannot  understand 
what  we  are  about  in  the  world  unless  we  know  some- 
thing about  them.     They  will  be  described  as  we  go  on. 

§  30.  Air. — Because  the  air  is  so  soft  that  we  can 
move  through  it  easily,  because  we  can  see  through  it  so 
well,  and  because,  when  pure,  it  has  neither  taste  nor 
smell,  we  are  apt  to  think  that  it  is  not  there.  But  think 
of  the  wind,  which  is  moving  air,  how  it  presses.  Or  fill 
a  well-made  paper-bag  with  air,  and  screw  up  its  mouth 
and  squeeze  it,  you  find  that  it  will  not  easily  give  in. 
So,  though  we  do  not  see,  or  taste,  or  smell  the  air,  and 
only  feel  it  when  it  blows  or  we  pass  through  it  quickly, 


AIR.  29 

yet  wo  know  it  is  matter.  But  it  is  not  like  stone,  which 
is  a  solid,  nor  like  water,  which  is  a  liquid  :  it  is  a  gas. 
Air  contains  and  is  wholly  made  of  four  gases.  Two  of 
these  are  elements — namely,  Nitrogen  and  Oxygen — and 
they  together  form  hy  far  the  largest  part  of  the  air.  Two 
of  them  are  compounds— namely,  Water  and  Carbonic 
Acid.  Water  is  made  of  oxygen  and  hydrogen.  Carbonic 
acid  is  made  of  oxygen  and  Carbon.  So  that  the  air  is 
made  of  four  elements — Nitrogen,  Oxygen,  Hydrogen, 
and  Carbon.  Although  nitrogen  forms  about  four-fifths 
of  the  air — that  is,  in  every  five  gallons  of  air  there  are 
four  of  nitrogen — yet  we  shall  seldom  have  to  speak 
about  it  again  in  this  book.  The  gas  carbonic  acid  is  the 
gas  which  is  seen  to  rise  as  hubbies  when  a  bottle  of  beer, 
or  ginger-beer,  or  soda-water  is  opened.  It  has  a  pleasant 
taste,  a  little  sharp;  and  liquids  which  usually  contain  it 
are  flat  when  it  is  not  there.  When  animals  breathe  in 
and  out,  the  air  which  they  breathe  out  contains  more 
carbonic  acid  than  the  air  they  drawr  in.  Although  a 
thousand  gallons  of  air  contain  less  than  half-a-gallon  of 
carbonic  acid,  this  small  quantity  of  carbonic  acid  is  of 
the"  greatest  importance,  because  it,  together  with  water, 
forms  the  chief  food  for  plants. 

You  know  what  Charcoal  is  like.  If  you  bake  a 
piece  of  wood  for  a  long  time  at  such  a  great  heat  that  it 
nearly  catches  fire,  but  not  quite,  you  find  it  changed  to 
charcoal  (charred).  Charcoal  is  nearly  pure  carbon.  The 
ash  which  is  left  when  charcoal  is  burnt  is  almost  the 
onty  part  of  the  charcoal  which  is  not  carbon.  This  ash 
contains  all  the  mineral  or  earthy  matter  which  the  plant 
has  got  from  the  earth.  The  whole  of  the  carbon  has 
been  got  from  the  air,  and,  of  course,  from  that  part  of 
the  air  which  contains  carbon — namely,  the  carbonic 
acid.  Thus  you  see  how  useful  this  small  quantity  of 
carbonic  acid  is ;  without  it,  plants  could  not  grow,  and 
therefore  all  animals  would  die;  for  all  animals  either 
live  on  plants,  or  on  other  animals  which  do  so. 


30  FIRE. 

Questions. — What  is  an  element  ?  How  m-any  elements  are  there 
in  water?  How  many  in  salt?  How  many  in  sugar?  How 
many  in  glue  ?  About  how  many  elements  are  known  ?  How  do 
we  judge  air  to  be  matter  ?  Of  what  two  gases  is  air  chiefly  made  ? 
How  many  gallons  of  each  are  there  in  a  hundred  gallons  of  air  ? 
What  two  other  gases  are  there  in  the  air  ?  What  elements  is  water 
made  of?  What  elements  is  carbonic  acid  made  of?  In  what 
drinks  is  carbonic  acid  found  ?  How  much  carbonic  acid  is  there 
in  a  thousand  gallons  of  air  ?  What  about  the  breath  of  animals 
in  regard  to  carbonic  acid  ?  What  is  charcoal  ?  Where  do  plants 
get  their  carbon  from  ?  Where  do  plants  get  the  stuff  which  is 
found  in  their  ashes  ? 


IX. 

Fire. 

Things  to  be  Seen. — Sugar  dissolving  in  water — charcoal 
burning  in  air — rusted  iron — flint  and  sand. 

§  31.  Fire. — When  charcoal  is  burnt,  I  said,  nothing 
is  left  but  ashes.  What  becomes  of  the  carbon  1  Burnt 
away.  Yes ;  but  away  where  to,  and  how  1  When  you 
put  a  lump  of  sugar  into  a  basin  of  water,  the  sugar  melts 
away ;  you  can  see  it  no  more.  But  you  know  that  it  is 
there ;  you  know  that  if  you  were  to  let  the  water  dry  up, 
you  would  find  the  sugar  again.  You  cannot  destroy 
matter.  What  happens  to  the  carbon  of  the  charcoal  is 
this  :  it  unites  with  the  oxygen  in  the  air,  and  with  it 
forms  carbonic  acid,  and  this  spreads  and  mixes  with  the 
air.  It  is  a  gas  as  colourless  as  air;  and  because  you  can 
see  through  it  so  well,  you  can't  see  it,  just  as  by  some 
lights  you  can't  see  a  sheet  of  glass.  The  burning  of  the 
charcoal  is  therefore  the  act  of  its  uniting  with  the 
oxygen  in  the  air  :  such  uniting  is  called  combustion, 
and,  more  exactly,  oxidation. 

Busting  is  another  common  instance  of  oxidation.  A 
piece  of  iron  exposed  to  the  air,  if  the  air  be  moist,  tar- 
nishes and  rusts.  It  slowly  unites  with  the  oxygen  of 
the  air.  But  the  result  of  such  union  is  the  red-brown 
solid  body  called  rust,  instead  of  being  a  gas,  as  is  the 


FUIE.  31 

case  with  carbon.  The  carbon  which  has  boon  partly 
burnt  away  of  course  weighs  less  than  at  first.  The  iron 
which  has  rusted  weighs  more  as  long  as  the  rust  sticks 
to  it,  because  all  the  iron  is  there,  together  with  oxygen. 
Of  course  if  the  rusted  iron  be  cleansed  from  rust,  it 
Aveiglis  less  than  it  did  at  first,  because  then  all  the 
oxygen  is  taken  away  again,  together  with  the  iron  with 
which  it  is  united. 

The  body  formed  when  a  substance  unites  with  oxygen 
is  called  the  oxide  of  that  substance.  Thus  carbonic  acid 
is  -an  oxide  of  carbon  ;  rust  of  iron  is  an  oxide  of  iron ; 
flint  or  silica  is  an  oxide  of  silicon,  and  so  on. 

Notice,  that  plants,  while  they  grow,  take  carbon  out  of 
the  carbonic  acid  of  the  air,  whereas,  when  the  carbon  of 
plants  is  burnt,  carbonic  acid  enters  the  air  again  ;  so  that 
when  you  set  lire  to  a  thing,  you  set  it  oil'  oxidising,  and 
it  may  get  far  hotter  than  you  made  it.  It  comes  to  this — 
in  order  to  start  it  burning,  you  must  heat  it  with  oxygen, 
that  is,  in  the  air.  The  part  you  start  burning  is,  while 
burning,  hot,  and  heats  the  rest  enough  to  start  it  burning, 
and  so  on.  Think  how  a  fire  spreads.  Different  bodies 
have  to  be  heated  to  different  degrees  in  the  air  before 
they  catch  fire ;  and  when  burning,  they  are  not  all  equally 
hot.  Even  the  same  substance  when  burning  may  be 
hotter  at  one  time  than  at  another.  The  quicker  any 
substance  burns,  the  hotter  it  is  while  burning,  but  of 
course  the  sooner  it  is  burnt  out.  In  the  one  case,  you 
have  a  lesser  hotness  for  a  longer  time ;  in  the  other,  a 
greater  hotness  for  a  shorter  time.  The  one  just  makes 
up  for  the  other.  Hotness  is  often  called  "  temperature/' 
Though  a  coal  burns  when  in  the  tire,  it  soon  goes  out 
when  taken  from  the  grate.  The  burning  part  throws  off 
so  much  heat  into  the  air,  that  it  cools  itself,  and  has  no 
heat  to  spare  to  set  fire  to  the  rest.  But  two  or  threo 
red-hot  coals  close  together  keep  on  burning  at  the  parts 
facing  one  another,  because  the  heat  which  one  throws  off 
in  burning  is  caught  by  the  others,  and,  so  little  heat  bdng 


32  EIRE,  FLAME. 

able  to  escape  in  this  way,  the  heat  of  burning  keeps  the 
burning  up.  A  iire  is  usually  laid  in  a  grate  by  first 
putting  in  paper,  then  wood  on  the  top  of  the  paper,  and 
coal  on  the  wood,  the  whole  being  so  built  that  air  can 
pass  freely  amongst  it.  Paper  is  easily  set  fire  to,  because 
it  is  so  thin  that  it  is  easily  heated  through  sufficiently 
hot  to  burn.  Paper  burns  with  a  flame,  and  this  flame 
laps  round  the  wood,  and  heats  it  hot  enough  to  set  it  on 
fire.  The  wood,  too,  burns  with  a  flame,  which  enters 
amongst  the  coal,  and  sets  fire  to  the  faces  of  the  coal, 
which,  for  the  above-given  reason,  do  not  go  out  when 
several  are  facing  one  another.  The  coal  itself  generally 
burns  with  a  flame,  and  this  helps  the  tire  to  spread. 
Coke  has  little  or  no  flame,  and  that  is  why  it  is  hard  to 
light  a  coke  fire  with  wood  alone,  and  why  the  fire  in  a 
grate  full  of  coke  spreads  so  slowly. 

Questions. — What  becomes  of  the  carbon  of  the  wood  when  the 
wood  is  burnt  ?  What  is  burning,  or  combustion  ?  What  is  rust- 
ing? What  is  rust  ?  How  is  it  that  iron  gets  heavier  as  it  rusts? 
What  is  meant  by  an  oxide  ?  How  is  it  that  a  fire  spreads  ?  How 
is  it  that  a  fire  burns  in  a  grate,  but  a  red-hot  coal  soon  goes  out 
if  taken  out  of  the  fire  ?  In  lighting  a  fire,  why  is  paper  used  ? 
Why  is  wood  used  ?  How  is  it  that  fire  spreads  so  slowly  through 
coke  ? 


X. 

Fire,  Flame. 

Things  to  be  Seen. — A  burning  coal  fire — soot — a  gas- 
fiame  (a  candle-flame  will  do  nearly  as  well) — a  clean 
metal  spoon — a  bright  table-knife — a  bottle  of  lime- 
water — a  tumbler — a  card  'or  plate  to  cover  the 
tumbler — some  vinegar. 

§  31  (continued). — A  coal  fire  is  the  oxidation  of  coal 
— that  is,  coal  being  oxidised.  Coal  contains,  and  is 
entirely  made  up  of  the  following  elements  : — Carbon, 
Oxygen,  Hydrogen,  Nitrogen,  Sulphur,  and  about  eight 
elements  and  metals  which  are  found  in  the  ash.     But 


FIRE,  FLAME.  33 

carbon  is  the  chief  thing  in  coal.  Different  kinds  of  coal 
contain  these  elements  in  different  quantities.  A  hundred 
pounds  of  some  kinds  of  coal  leave  as  much  as  six  pounds  of 
ash,  of  others  only  one  pound.  Nobody  knows  how  these 
elements  are  united  with  each  other  in  the  coal.  The 
ash  we  need  not  care  about  now.  The  elements  of  the 
coal  which  burn  are  the  carbon,  hydrogen,  and  sulphur. 
The  oxygen  and  hydrogen  are  united  with  some  of  the 
carbon  as  they  were  when  the  coal  was  wood.  The 
sulphur  is  not  only  useless,  but  is  a  nuisance  in  the  coal. 
It  burns,  and  some  of  its  oxide  is  found  in  the  ash,  some 
of  it,  incompletely  burnt,  goes  up  the  chimney,  and 
makes  the  air  of  cities  where  coal  is  burnt  sour.  The 
carbon  and  hydrogen  are  completely  oxidised  in  a  clear 
fire,  partly  by  the  oxygen  in  the  coal ;  but  as  this  is  not 
nearly  enough  to  burn  them,  they  are  burnt  by  the  oxygen 
of  the  air  which  enters  the  grate.  The  carbon  is  burnt 
to  carbonic  acid  (see  §  32),  and  the  hydrogen  to  water 
(see  §  33).  The  nitrogen  in  the  air  and  the  nitrogen 
already  in  the  coal  rise  up  the  chimney ;  so  that  the  gases 
rising  up  the  chimney  from  a  clear  burning  coal  fire  are 
carbonic  acid,  water,  nitrogen,  and  oxidised  sulphur.  All 
these  are,  at  this  hotness,  colourless  invisible  gases.  From 
most  coal  fires  smoke  arises  from  the  upper  part  of  the 
fire;  this  is  because  there  is  not  enough  air  passing 
through  the  fire,  and  because  the  heat  there  is  not  strong 
enough ;  in  fact,  the  coal  is  being  partly  distilled,  as  in 
making  coke,  and  the  visible  smoke  is  a  dense  tar  and 
particles  of  carbon.  These  collect  either  in  the  chimney 
or  in  the  air,  and  are  known  as  Soot.  Soot  is  wasted 
fuel. 

§  32.  Flame. — The  substances  which  we  have  been 
examining  as  givers  of  light  all  burn  with  a  flame.  If 
you  turn  down  a  gas-flame  till  it  is  only  about  an  eighth 
of  an  inch  long,  it  burns  blue  and  gives  but  little  light  ; 
a  hundred  of  such  little  blue  flames  would  not  give 
enough  light  to  read  by ;  or  if  you  blow,  or  if  the  wind 
c 


34  FLAME. 

blow  pretty  hard  upon  a  gas-flame  which  is  giving  light, 
the  flame  is  blown  on  one  side,  turns  blue,  and  gives 
scarcely  any  light.  In  the  last  case,  in  the  blue  flame 
which  gives  no  light,  as  much  gas  comes  out  of  the  pipe 
and  is  burnt  as  before  it  was  blown,  and  the  flame  is  not 
smaller.  How  is  it  that  the  one  flame  gives  more  light 
than  the  other?  Put  now  the  end  of  a  spoon  or  any 
body  which  will  not  burn  for  a  few  seconds,  first  into  the 
light-giving  flame  where  the  light  is  strongest,  you  find  it 
covered  with  soot ;  wipe  it  and  put  it  in  the  flame  which 
is  quite  blue  and  gives  so  little  light,  and  you  will  see 
that  the  spoon  remains  clean.  And  so  whenever  burning 
gas  gives  its  yellowish-white  light  there  is  Soot  in  the 
flame.  Soot  is  very  nearly  pure  carbon,  and  is  also  called 
Lamp-black.  When  there  is  no  soot,  there  is  only  the 
feeble  blue  light.  Now  let  the  gas  burn  so  as  to  giv^its 
proper  yellowish-white  light,  and  hold  the  spoon  above 
the  flame — it  remains  bright.  This  shows  that  it  is  the 
hot  soot  which  gives  the  yellow  light,  and  that  the  soot 
exists  only  in  the  flame.  Take  the  bright  spoon  again,  or 
a  bright  table-knife  blade,  and  let  it  be  quite  cold ;  hold 
it  above  the  flame  for  a  second  only,  and  examine  it 
instantly,  and  you  will  find  it  covered  with  a  dew,  as 
though  you  had  breathed  on  it.  This  dew  is  water. 
This  takes  place  however  dry  the  air  of  the  room  is,  and 
however  dry  is  the  coal-gas ;  so  that  this  water  is  formed 
in  the  flame.  Now  take  some  water  which  has  been 
shaken  with  slaked  lime  (see  §  3)  and  become  clear  (it  is 
called  lime-water).  Hold  a  cold  dry  tumbler  over  the  gas- 
flame  for  a  second  or  two,  turn  out  the  gas,  cover  the 
mouth  of  the  tumbler  with  a  sheet  of  cardboard,  turn  the 
tumbler  and  card  over,  pour  a  little  of  the  lime-water 
into  the  tumbler,  put  on  the  card,  and  twirl  the  tumbler 
round.  The  lime-water  will  become  milky,  and  the 
milkiness  wdl  settle  down.  This  white  substance  is 
nothing  but  lime  united  with  carbonic  acid ;  and  you 
can  show  that  it  contains  carbonic  acid  by  pouring  off 


FLAME.  35 

most  of  the  liquid  above  it  and  adding  a  little  vinegar, 
whereupon  it  will  froth  up.  This  frothing  is  the  rising 
through  the  liquid,  and  escape  into  the  air,  of  hubbies  of 
carbonic  acid.  This  carbonic  acid,  like  the  water,  has 
been  formed  in  the  flame. 

Questions. — What  is  coal  chiefly  made  of?  Which  elements  of 
the  coal  burn?  What  gases  are  formed  when  coal  is  burning? 
What  other  gas  goes  up  the  chimney  ?  What  is  smoke  ?  What  is 
soot  ?  How  can  it  be  shown  that  when  coal-gas  burns,  water  is 
formed  ?  How  that  carbonic  acid  is  formed  ?  How  is  it  that  there 
is  soot  in  a  bright  gas-flame,  and  none  when  the  flame  is  burning 
blue?  What  becomes  of  the  soot  in  a  bright  flame?  What  is 
lime-water?  What  is  the  milkiness  which  carbonic  acid  makes  in 
lime-water  ?  How  would  you  show  that  this  milkiness  contains  a 
gas? 


XI. 

Flame. 

Thikgs  to  be  Seen; — A  burning  candle — a  large  draw- 
ing of  a  candle-flame — a   tallow   candle   (§   41)   or 
dip — a  composite  or  stearine  candle  (§  44) — an  air-gas 
burner. 
§  32  (continued). — Let  us  now  look  very  carefully  at  a 
candle  burning  steadily  in  a  dark  room.     You  see  at  the  top 
a  cup  of  melted  tallow  or  stearine  or  paraffin,  or  of  whatever 
else  the  candle  is  made.     The  solid  is  melted  of  course  by 
the  heat  thrown  off  by  the  flame.     Rising  through  the 
middle  of  this  stands  up  the  wick,  which  is  still  unburnt 
and  unblackened  in  the  liquid,  and  a  little  way  above. 
Just  where  the  flame  begins  the  wick  is  charred  black, 
and  all   the  rest  of  the  wick  is  black  except  the   tip, 
which,  if  the  wick  is  made  to  curl  (see  §  41),  as  most 
wicks  are  now  made  to  do,  is  red-hot,  and  is  manifestly 
burning  away  like  a  hot  coal,  leaving,  however,  little  or 
no  ash,  because  the  cotton  is  made  of  little  else   than 
carbon,  oxygen,  and  hydrogen — that  is,  it  is  a  substance 
containing  and  consisting  of  these  elements.       The  real 


36  FLAME. 

purpose  of  the  wick,  however,  is  not  to  hum ;  for  one  can 
use  metal  wicks ;  not  well,  it  is  true,  with  candles  where 
the  level  of  the  "burning  matter  is  always  sinking,  and 
which  would  so  leave  the  metal  sticking  out  too  far,  hut 
with  oil  lamps,  where  the  level  of  the  burning  matter  can 
he  kept  pretty  constant.  The  real  purpose  of  the  wick  is 
to  hecome  soaked  with  the  liquid  matter  (say  stearine). 
For,  like  all  finely  fibrous  or  porous  solids,  a  mass  of 
cotton  gets  wetted  with  a  liquid  a  good  way  up,  when  its 
lower  part  dips  into  that  liquid.  When  the  liquid 
reaches  the  flame,  it  is  first  simply  distilled — that  is,  made 
hy  the  heat  into  a  vapour  or  gas.  Any  of  it  which 
cannot  so  rise  remains  on  the  wick.  This  vapour  forms 
the  inner  part  of  the  flame,  and  you  can  easily  see  that  it 
is  dark ;  in  fact,  there  is  really  no  flame  in  this  part  at 
all.  Outside  this  is  the  proper  light-giving  part.  In  this 
part  the  hydrogen  of»  the  stearine  is  burning,  water  heing 
here  formed.  The  carbon  of  the  stearine  is  therefore 
deprived  of  its  hydrogen.  The  hurning  of  the  hydrogen 
gives  rise  to  an  exceedingly  great  heat,  and  this  heat 
makes  the  particles  of  carbon  white-hot.  Further  up  in 
the  flame,  and  at  the  sides  of  this  light-sheath,  you  see  a 
faint  bluish  sheath.  It  is  here,  and  at  the  outer  edge  of 
the  light-cone,  that  the  carbon  is  burnt,  and  also  at  the  end 
of  the  wick.  The  reason  why  dips  (see  §  41)  with  straight 
wicks  want  snuffing  is  that,  as  soon  as  the  top  of  the 
wick  finds  itself  in  the  light-flame,  it  gets  coated  with 
soot  and  swells,  and  so  stops  the  gas-currents  of  the 
flame,  thus  making  the  flame  still  more  smoky.  And 
"besides,  the  part  of  the  tallow  which  heat  cannot 
volatilise  gathers  there ;  whereas  in  the  curled  wick  this 
is  exposed  to  the  hot  air,  and  is  "burnt  off.  All  through 
the  flame,  in  all  its  parts  excepting  the  inner  parts, 
the  nitrogen  of  the  air  is  rushing.  The  shape  of  the 
flame  is  given  by  the  upward  rush  of  the  hot  gases,  and 
the  inward  rush  of  the  surrounding  air. 

The  gas-burners  called  air-gas  burners  show  that  the 


FLAME,  WATER.  37 

light-giving  power  of  flames  is  due  to  the  existence  in 
them  of  unburnt  carbon.  In  these  burners  coal-gas 
enters  one  end  of  a  metal  tube  and  burns  at  the  other. 
]5ut  just  where  it  enters  the  tube  there  are  some  holes. 
The  upward  current  of  the  coal-gas  draws  air  in,  and  this 
mixes  with  the  gas,  so  that  when  they  both  reach  the 
flame  there  is  enough  oxygen  to  burn  the  carbon  as  well  as 
the  hydrogen  at  once  ;  so  that  there  is  no  stage  where  the 
carbon  is  heated  white-hot  by  the  heat  of  the  burning 
hydrogen.  A  common  gas-burner  gives  out  just  as  much 
heat  as  an  air-gas  burner  if  they  both  burn  the  same 
quantity  of  gas.  But  the  air-gas  burner's  flame  is  not  so 
smoky  inside. 

Questions. — What  is  the  use  of  the  wick  in  a  candle?  What 
happens  first  to  the  melted  stuff  when  it  creeps  up  to  the  flame  ? 
What  is  in  the  very  inside  of  a  candle  flame  ?  What  is  taking 
place  in  that  part  of  the  flame  which  gives  out  light  ?  What  sub- 
stance is  there  found?  What  is  it  which  gives  out  light?  What 
takes  place  outside  the  light-giving  part  of  the  flame?  Why  do 
dips  need  snuffing  ?  Why  are  plaited  wicks  used  ?  What  is  an 
air-gas  burner,  and  why  is  it  sometimes  used  ? 


XII. 

Water. 

Things  to  be  Seen. — A  kettle  of  toiling  muddy  water — 
the  steam  from  it  cooled  on  a  plate  and  drops  of  dis- 
tilled water  formed — apiece  of  porous  sandstone  loith 
a  hollow  in  it — muddy  water  filtered  through  the  sand- 
stone. 
§  33.  Water. — Water  is  a  union  of  the  gas  Oxygen 
with  the  gas   Hydrogen  ;    it  is  therefore  an    oxide    of 
hydrogen.       Two   gallons    of   hydrogen    must   have    one 
gallon  of  oxygen  to  burn  to  water.     A  gallon  of  oxygen 
is  sixteen  times  as  heavy  as  a  gallon  of  hydrogen,  so  that 
to  burn  to  water  one  pound  of  hydrogen  eight  pounds 
of  oxygen  are  needed.     Hydrogen  is  not  found  by  itself 
anywhere  on  the  earth,  or  even  mixed  with  other  gases, 


38  WATER. 

as  nitrogen  and  oxygen  are  in  the  air.  Of  course  the 
vapour  of  water  contains  hydrogen,  and  so  therefore  does 
moist  air.  Marsh  gas  also  contains  hydrogen,  but  in  this 
case  the  hydrogen  is  united  with  carbon  (see  §  40). 
Hydrogen  is  the  lightest  stuff  known.  The  water  which 
we  find  in  the  sea,  in  rivers,  lakes,  springs,  and  wells,  is 
never  quite  pure.  But  if  you  hold  a  cold  plate  against 
the  spout  of  a  kettle  of  boiling  water,  you  will  get  a  few 
drops  of  nearly  pure  water.  This  is  distilled  water.  You 
all  know  how  the  rain  falls  from  the  sky,  and  how  the 
rain-water  collects  in  little  brooks  and  streams  and  rivers, 
how  it  flows  down  to  the  sea,  and  how  the  sun  shining  on 
the  sea  is  always  at  work  drying  up  the  sea  and  raising 
its  water  to  the  sky  from  which  it  fell.  It  would  be  as 
unwise  to  look  upon  the  sea  as  the  original  source  of 
water,  as  it  would  be  to  look  upon  the  sky  as  the  original 
source.  The  hen  gives  rise  to  the  egg,  and  the  egg  to  the 
hen.  Let  us  consider  a  falling  rain-drop.  At  first  it  is  as 
pure  water  as  that  which  you  collected  on  the  plate  from 
the  kettle  of  boiling  water.  Eut  as  it  falls  through  the  air 
it  absorbs  a  little  oxygen  and  carbonic  acid.  These  enable 
the  water  to  eat  away  rocks  and  earths.  If  a  rock  is 
made  up  of  grains  of  two  kinds  of  substances,  and  if  one 
of  these  substances  dissolves  out  in  the  rain-water,  the 
other  will  be  left  full  of  holes  and  crumbly,  and  so  it  may 
crumble  to  pieces  and  become  mud.  If  the  rain-water 
flows  at  once  to  a  rapid  brook,  and  so  to  a  rapid  river, 
and  on  to  the  sea,  the  part  of  the  rock  truly  dissolved  and 
the  mud  reach  the  sea  together.  The  mud  there  settles, 
but  the  truly  dissolved  rock  does  not.  If  the  rain-water, 
after  reaching  the  earth,  meets  with  openings  in  the 
ground  or  porous  rocks,  it  becomes  filtered  from  mud, 
the  particles  of  which  cannot  get  through  the  very  fine 
holes  in  the  rock,  but  the  water  has  plenty  of  chance  of 
dissolving  all  it  can  of  such  rocks.  If,  then,  the  water 
breaks  out  at  a  lower  level,  it  is  called  a  spring,  and 
spring-water  is  generally  clear  and  bright,  but  contains 


WATER.  39 

more  dissolved  rock  than  river-water  docs.  Tlicro  arc, 
then,  the  three  qualities  of  natural  water — Bain-water, 
which  contains  no  solid  matter,  and  is  called  Soft, 
because  it  feels,  when  rubbed  between  the  hands,  as  if 
there  were  a  little  soap  in  it;  liiver-water,  which  is 
generally  muddy,  and  contains  animal  and  vegetable 
matter  drained  into  it  from  the  surface  of  the  land,  and 
little  animals  which  live  on  such  matter,  and  some 
mineral  matter  in  solution,  which  last  makes  it  somewhat 
hard ;  and,  lastl^^,  Spring-water,  which  is  clear,  but 
generally  harder  than  river-water.  Wells  are,  of  course, 
artificial  springs,  and  the  water  in  them  is  spring- water. 

Question?  —What  is  water  made  of?  How  many  pints  of  oxygen 
are  needed  to  burn  four  pints  of  hydrogen  ?  How  many  pounds  of 
oxygen  are  needed  to  burn  one  pound  of  hydrogen  ?  How  many 
pounds  of  oxygon  and  how  many  pounds  of  hydrogen  are  there  in 
eighteen  pounds  of  water  ?  How  can  distilled  water  be  got  from 
dirty  water  ?  What  is  a  drop  of  rain  when  it  reaches  the  earth 
besides  water  ?  How  does  rain  attack  rocks  ?  What  do  brooks 
and  rivers  carry  along  besides  water  ?  What  is  a  spring  ?  and  how 
does  spring-water  differ  from  river-water  ?  How  do  rain-water, 
river-water,  and  spring-water  differ  from  one  another  ?  What  is 
meant  by  hard  water  ? 


XIII. 

Water  (continued). 

Things  to  be  Seen. — A  lump  of  ice  floating  in  a  tumbler 

of  icater,  showing  (1)  the  dew  on  the  outside  of  the 

glass,  and  (2)  the  lightness  of  the  ice. 

§  33  (continued). — The    sunshine  falling  on   the  sea 

and  the  surfaces  of  lakes  and  rivers  ami  the  moist  earth, 

warms  them,  and  so  warms  the  air  which  touches  them. 

The  warmer  the  air  is,  the  more  water  it  takes  up.     The 

water  enters  the  air  from  such  surfaces  in  the  form  of  gas, 

which  you  cannot  see  any  more  than  you  can  see  the  air 

itself.     Then  if  such  warm  moist  air  becomes  cooled,  as  it 

may  do  hy  moving,  as  wind,  to  a  cooler  place,  it  can  no 

longer  keep  so  much  water.     The  water  separates  from  it 


40  WATER. 

in  very  small  drops.  If  you  are  amidst  such  a  mass  of 
small  drops,  you  call  it  a  mist;  if  you  see  it  from  a 
distance,  you  call  it  a  cloud.  When  the  air  between  the 
cloud  and  the  earth  has  as  much  water  as  it  can  hold,  the 
drops  from  the  cloud,  when  they  have  stuck  together  so 
as  to  form  large  drops,  fall  through  the  air  as  rain.  But 
rain-drops  falling  from  a  high  cloud  may,  if  they  fall 
through  dry  air,  dry  up  and  quite  vanish  before  they 
reach  the  earth. 

It  often  happens  that  the  moist  air  is  chilled  so  much 
that  the  water  in  it  is  not  only  separated  out  as  mist,  but 
the  little  drops,  of  which  the  mist  is  made,  themselves 
freeze  and  become  ice ;  these  may  stick  together  and 
reach  the  earth  as  snow.  Rain-drops,  again,  may  fall 
through  air  which  is  so  cold  that  they  freeze,  and  they 
then  fall  as  hail. 

Water  also  comes  out  of  the  air  as  dew  and  hoar-frost. 
You  have  noticed  that  when  a  red-hot  poker  is  taken  out 
of  the  fire,  you  cannot  hold  your  hand  very  near  it.  It 
throw's  off  its  heat  through  the  air  to  your  hand.  So  the 
wet  earth,  which  has  got  hot  in  the  sunshine,  and  made 
the  air  touching  it  as  warm  and  as  moist  as  such  warm 
air  can  be,  throws  off  its  heat  at  night  through  the  air,  so 
that  its  surface  gets  cooler  than  the  air  which  touches  it. 
This  surface  cools  this  air  touching  it,  and  the  air  in 
cooling  must  give  up  water,  because  cold  air  cannot  hold 
so  much  water  as  warm,  and  the  water  thus  given  up  lies 
upon  the  earth,  and  is  called  dew.  Frozen  dew  is  hoar 
frost.  I  do  not  mean  that  the  dew  is  formed  and  then 
frozen,  but  that  it  freezes  as  it  is  formed. 

When  water  freezes,  it  swells  and  gets  more  bulky ;  so 
that,  although  a  piece  of  ice  weighs  just  as  much  as  the 
water  from  which  it  was  formed,  it  is  larger.  Thus,  if 
you  take  equal  sizes  of  water  and  ice,  the  ice  is  the 
lighter ;  you  know  it  floats  on  water.  One  effect  of  the 
swelling  of  ice  as  it  is  formed  is  this — water  in  pipes  will 
burst  them   when  the  water   freezes  in  them.     This  is 


WATER.  41 

generally  only  noticed  when  the  thaw  sets  in,  and  the  ice 
again  becoming  water  can  run  out  of  the  crack.  When 
water  penetrates  earth,  or  even  hard  rucks,  and  then 
freezes,  it  forces  the  parts  asunder  and  softens  them. 
This  is  good  for  plants,  which  get  all  their  food  except 
carbon  from  the  soil. 

Questions. — What  becomes  of  water  when  it  is  warmed  with  air? 
What  takes  place  in  warm  wet  air  when  it  is  cooled  ?  What  is  a 
mist?  What  is  a  cloud  ?  What  is  the  cause  of  rain?  What  is 
snow?  What  is  hail?  How  is  dew  formed  ?  How  is  hoar-frost 
formed  ?  How  do  you  know  that  ice  is  lighter  than  water?  Why 
do  water-pipes  burst  when  the  water  iu  them  freezes  ?  What 
happens  to  wet  rocks  when  the  water  in  them  freezes  ?  How  does 
the  breaking  of  rocks  by  frost  do  good  to  plants  ? 


PART    III. 

WOOD. 

XIV. 

Things  to  be  Seen. — As  many  different  hinds  of  sprout- 
ing seed  as  can  he  got,  such  as  acorns,  horse-chestnuts, 
beech-nuts,  which  have  been  sprouting  for  about  a  week 
or  a  fortnight,  or  mustard  and  cress — horse-chestnuts 
or  walnuts  carefully  peeled — a  few  young  trees  grown 
from  seed,  about  two  years  old — slices  of  young  tree- 
stems  cut  so  as  to  show  the  rings  of  ivood  and  the  bark 
(failing  these,  have  good  drawings  of  them) — as  many 
different  kinds  of  'wood,  smoothed,  as  can  be  got. 

§  34.  Wood. — When  an  egg  is  kept  warm  from  the 
time  it  is  laid,  a  chicken  is  formed  in  it  without  any  food 
reaching  it  from  the  outside.  The  yolk  gradually  takes 
the  form  of  the  bird,  and  both  the  yolk  and  the  white 
are  used  up  for  this  end.  ISo  when  an  acorn  feels  the 
dampness  and  warmth  of  spring,  its  hard  shell  is  softened 
and  burst  by  the  swelling  kernel.  Then  it  is  seen  that 
the  kernel  is  made  of  three  things,  which  partly  separate, 
two  naps  and  a  germ.  The  germ  divides  into  two 
branches ;  one  rises  above  the  earth  and  forms  the  future 
stem  or  trunk  of  the  oak,  the  other  enters  the  ground. 
The  young  plant  gets  its  food  from  the  two  flaps  which 
formed  a  part  of  the  original  seed,  until  it  is,  as  it  were, 
weaned,  and  able  to  get  its  own  food  from  earth  and  air. 
To  get  food  from  the  air  it  wants  leaves;  and  the  rising 
stem  carries  buds,  which  grow  and  open  into  leaves.     The 


wood.  43 

flaps  are  by  this  time  drained  dry;  they  wither  and  fall 
off.  The  root  grows  and  sends  oil'  side  roots,  so  that  the 
plant  gets  a  firmer  grip  of  the  ground  as  it  gets  taller. 
From  the  earth,  mineral  matter  dissolved  in  the  water, 
and  water  itself,  enter  the  roots  and  rise  in  the  stem  to 
the  leaf.  By  the  joint  working  of  light  and  the  green 
stuff  in  the  leaf,  the  leaf  breaks  the  carbonic  acid  of  the  air, 
rejecting  some  of  its  oxygen,  but  keeping  its  carbon  ;  and 
out  of  this  and  the  mineral  matter  the  leaf  makes  a  liquid 
which  has  nearly  the  composition  of  wood.  This  liquid 
comes  down  again,  and  hardens  into  wood  between  the 
original  stalk  and  its  skin ;  it  gives  something  to  the 
skin,  and  makes  it  into  young  bark,  which  is  inside  the 
last  year's  bark.  It  gives  something  to  the  stem  or  trunk. 
A  casing  of  new  wood  is  thus  formed  every  year  beneath 
the  bark,  and  the  bark  itself  grows  in  thickness.  Wood 
consists  of  carbon,  oxygen,  hydrogen,  and  some  mineral 
matter. 

*  §  35.  If  you  cut  a  young  tree  down,  and  flatten  and 
smooth  the  stump,  you  will  see  on  the  outside  a  ring  of 
bark,  then  rings  of  wood  one  within  the  other,  and  in  the 
middle  of  all  the  rings — that  is,  in  the  middle  of  the  tree — 
a  little  circle  of  pith.  If  the  tree  is  ten  years  old,  and 
bears  fresh  leaves  once,  and  only  once,  a-year,  you  will 
find  ten  such  rings  of  wood ;  and  so  there  will  be  twenty 
if  the  tree  is  twenty  years  old.  Thus  you  can  tell  the 
age  of  such  a  tree  when  it  is  cut  down,  unless  it  has 
decayed  away  and  got  hollow  in  the  middle,  by  counting 
its  rings  of  wood.  If  you  look  carefully,  you  will  see 
streaks  stretching  across  these  rings,  with  their  ends 
pointing  towards  the  centre  of  the  tree.  The  wood  quite 
in  the  centre  is  pith,  and  is  of  no  use  to  us.  The  wood 
next  to  the  bark  is  new  wood,  and  is  soft;  it  is  called 
sap-wood,  and  is  of  little  use.  The  wood  between  the  two 
is  the  firmest,  and  is  called  heart-wood.  "When  the  tree 
has  stopped  growing,  it  begins  to  decay,  and  the  pith  and 
heart-wood  begin  first.     So  that  it  should  be  felled  for 


44  wood. 

timber  at  a  certain  age,  which  differs  for  different  trees. 
Oaks  should  be  felled  when  about  a  hundred  years  old, 
ash  and  elm  at  about  seventy,  and  fir  at  about  eighty. 
Such  wood  is  the  best ;  but  more  wood,  though  of  a 
worse  kind,  can  be  got  off  the  same  land  if  the  trees  are 
cut  younger  and  oftener,  being,  of  course,  replanted. 
Trees  should  be  felled  either  at  mid-winter  or  in  the 
height  of  summer;  at  both  times  their  juices  are  at  rest. 
Felled  trees  with  their  branches  lopped  off  are  called  logs. 
If  wood  is  to  be  used  for  building,  the  bark  should  be 
taken  off  and  the  trunk  roughly  squared  ;  this  takes  off 
most  of  the  sap-wood,  and  allows  the  timber  to  dry 
equally.     Timber  in  this  state  is  called  a  "  balk." 

§  36.  There  are  two  chief  kinds  of  tree  the  wood  of 
which  is  used  in  buildings — Pine-wood  and  Leaf-wood. 
The  pine,  fir  (or  spruce),  larch,  cedar,  cypress,  and  yew 
give  pine-woods  ;  their  leaves  are  needle-shaped,  hard, 
and  smooth,  and  they  do  not  all  fall  off  in  the  autumn; 
their  fruit  is  something  like  the  cone  of  the  pine  or  fir- 
tree.  All  these  woods  contain  turpentine  (see  §  67). 
Such  pine-wood  is  generally  softer  than  leaf-wood.  Its 
fibres  are  long  and  straight.  It  stands  a  strong  pull 
along  the  fibre,  but  is  easily  crushed  from  end  to  end. 
It  is  elastic  across  the  fibres,  and  recovers  its  shape  when 
bent.  The  most  common  kinds  of  leaf-woods  or  hard- 
woods are : — Oak,  ash,  elm,  beech,  chestnut,  walnut, 
pear,  cherry,  poplar,  sycamore,  maple ;  and,  of  foreign 
woods,  boxwood,  greenheart,  ebony,  teak,  mahogany, 
rosewood,  hickory. 

Though  pines  and  firs  are  really  different  trees,  the 
wood  from  them  both  is  generally  called  pine-wood,  and, 
when  sawn  into  boards,  the  boards  are  called  Deals. 
Scaffold-poles  are  generally  the  barked  stem  of  the  larch ; 
and  ladders  are  made  of  the  same  sawn  down  the  middle 
from  end  to  end. 

Questions. — What  happens  to  an  acorn  when  it  sprouts  ?  Whence 
does  a  young  seedling  get  its  first  food  mainly  ?     What  is  the  good 


wood.  45 

of  a  plant's  roots  ?  What  is  tlie  good  of  its  leaves  ?  What  is  the 
use  of  the  green  stuff  in  leaves  ?  Where  is  the  new  plant-stuff 
made,  and  where  does  the  plant  store  it?  What  is  wood  made 
6f?  What  does  the  top  of  a  tree-stump  look  like  when  it  is 
smoothed  ?  How  can  you  judge  of  the  age  of  a  tree  by  the 
look  of  its  stump  ?  What  is  pith  ?  What  is  sap-wood  ?  What  is 
heart-wood?  At  what  seasons  should  trees  be  felled,  and  why? 
What  are  logs  ?  What  are  balks  ?  What  trees  give  pine-wood  ? 
What  substance  is  always  found  in  pine-woods  ?  What  are  the 
commoner  kiuds  of  leaf-wood?  How  does  pine-wood  differ  from 
leaf-wood  ? 


XV. 

Wood  (continued.) 

Things  to  be  Seen. — Planks — deals — battens— joists — 
laths — veneer — drawing  of  circular  saw. 
§  37.  Whatever  use  is  to  be  made  of  the  wood,  it 
must  always  be  seasoned — that  is,  dried.  It  is  not 
reckoned  thoroughly  seasoned  till  it  has  lost  about  a 
fifth  of  its  weight.  If  it  is  not  seasoned  before  it  is  used, 
it  warps — that  is,  it  cracks  and  bends  and  shrinks. 
Timber  which  is  to  be  used  as  balks,  as  for  large  beams 
of  roofs  or  ships,  only  needs  one  seasoning,  which  should 
last  between  one  and  two  years.  The  balks  are  piled  in 
a  stack  in  such  a  manner  that  the  air  can  play  round  each 
one,  and  they  are,  if  possible,  sheltered  from  the  rain. 
However  well  seasoned  the  balk  may  be,  when  it  is  cut 
up  the  pieces  warp  again  a  little  ;  so  they  have  to  be 
again  seasoned  before  being  finished.  The  balk  is  cut  np 
into  Planks,  Deals,  Battens,  and  so  on,  by  a  saw,  some- 
times by  hand,  sometimes  by  machinery.  In  the  common 
saw-pit  the  balk  is  laid  upon  two  supports  called  Tressels, 
one  end  sticking  over  one  of  the  tressels.  A  line  is 
marked  from  end  to  end  on  the  top  face  by  stretching  a 
chalked  string  above  it  and  plucking  the  string :  it 
strikes  against  the  wood  and  shakes  off  its  chalk.  This 
line  is  as  far  from  the  nearest  face  as  the  plank  has  to  be 
thick.     Then  one  sawyer,  standing  at  the  bottom  of  the 


46  wood. 

pit,  and  the  other  on  the  balk,  each  laying  hold  of  the  cross 
handles  of  the  long  and  wide  saw,  one  of  which  is  at  each 
end,  they  saw  the  balk  from  end  to  end.  If  the  pieces 
are  between  two  and  six  inches  thick  and  eleven  inches 
wide,  and  not  less  than  eight  nor  more  than  twenty-one 
feet  long,  they  are  called  "  planks."  Such  planks  are 
used  for  laying  down  on  rough  ground,  so  that  wheel- 
barrows may  move  easily.  They  are  strong  enough  to 
bear  a  heavy  weight  in  the  middle,  and  are  so  used  for 
the  platforms  of  scaffoldings  and  like  purposes.  If  the 
piece  is  only  nine  inches  broad,  and  not  more  than  four 
thick,  it  is  called  a  "  deal."  When  deals  are  less  than 
two  inches  thick  they  are  called  "  cut  deals."  If  the 
piece  be  only  seven  inches  broad  and  as  thick  as  a  deal, 
it  is  called  a  "  batten."  Cut  deals  and  battens  are  mostly 
used  for  boards  for  flooring. 

When  large  quantities  of  wood  are  to  be  cut,  the  saw  is 
worked  up  and  down  by  a  steam-engine,  or  by  the  force 
of  falling  water,  and  the  balk  is  pushed  up  against  the 
saw  by  the  same  power. 

A  still  quicker  way  of  sawing  the  timber  when  one  has 
a  great  water-fall,  or  can  afford  a  strong  steam-engine,  is 
by  use  of  a  round  saw.  This  is  a  circle  of  sheet  steel, 
with  saw-teeth  all  round  its  edge.  It  stands  upright, 
and  projects  through  a  slit  in  a  long  firm  bench.  The 
rod  or  axle  on  which  it  turns  is  below  the  bench ;  and 
the  part  of  the  saw  which  stands  above  the  bench  must 
stand  higher  than  the  top  face  of  the  timber  which  has  to 
be  sawn  through.  This  timber  is  pushed  forward 
between  uprights  called  guides. 

After  being  well  seasoned  as  balk  timber,  a  few  weeks' 
seasoning  after  sawing  into  planks,  deals,  or  battens  is 
enough.  The  planks  are  stacked  one  upon  the  other,  so 
that  their  own  weight  prevents  them  from  twisting. 
They  can  shrink,  and  because  their  edges  are  still  free — 
that  is,  not  nailed  down — they  shrink  without  cracking. 

The  larger  beams  of  houses  are  generally  made  of  pine 


wood.  47 

or  fir,  or  of  oak,  chestnut,  or  teak.  The  cross  pieces  of 
floors  upon  which  the  hoards  are  nailed,  and  which  are 
called  Joists,  are  of  pine,  and  so  are  the  boards  them- 
selves. If  the  lloor  is  not  to  be  carpeted,  and  if  it  is  to 
be  much  trodden  on,  oak  or  teak  is  often  used.  Ceilings 
are  generally  made  by  nailing  pieces  of  pine  split  into 
thin  and  narrow  strips  called  Laths,  and  covering 
these  with  plaster.  Walls  separating  rooms  on  the  same 
floor  are  often  made  in  the  same  way. 

Doors  are  generally  made  of  pine ;  sometimes  of  oak  or 
mahogany.  Chairs,  wooden  bedsteads,  tables,  and  sofas 
are  generally  made  of  beech ;  the  better  kinds  of  tables 
and  sofas  of  oak  or  mahogany.  Beech  tables  are  often 
"  Veneered"  with  mahogany — that  is,  thin  slices  of  the 
mahogany  are  glued  on,  being  nicely  fitted,  edge  to  edge. 
Handles  of  doors  and  drawers  are  often  of  ash  or  beech 
stained  black. 

Questions.  —  What  is  the  use  of  "  seasoning"  wood,  and  how  is  it 
seasoned?  How  are  balks  cut  up?  What  are  planks,  deals,  and 
battens  ?  How  is  a  circular  saw  used  ?  Of  what  woods  are  the 
larger  beams  of  houses  generally  made  ?  What  are  joists?  How 
are  ceilings  made  ?  What  is  veneer  ?  What  woods  are  used  for 
chairs,  wooden  bedsteads,  tables,  sofas,  door  handles,  and  drawer 
handles  ? 


PART    IV. 


HEATING    AND    LIGHTING. 

XVI. 

Charcoal,  Feat,  Coal-gas. 

Things  to  be  Seen. — Pieces  of  charcoal — peat  and  turf — 
coal-gas. 

§  38.  Charcoal. — If  wood  be  heated  in  a  Still  or 
Itetort,  as  coal  is  heated  when  coke  and  coal-gas  are  made 
(see  §§  2,  40),  a  quantity  of  tar  and  acid  liquid  (wood 
vinegar)  and  other  things  come  off,  and  what  remains  in 
the  still  or  retort  is  wood  charcoal.  This  body  is  nothing 
but  the  element  carbon,  along  with  the  earthy  matter  of 
the  wood.  But  in  most  countries  a  large  quantity  of 
charcoal  is  made  by  the  partly  stifled  burning  of  the 
wood  itself.  Small  logs  and  branches  cut  short  are 
piled  in  a  stack,  and  this  stack  is  covered,  excepting  in 
one  place  at  the  top,  with  earth.  The  stack  is  lighted  from 
below,  and  the  place  of  the  opening  above  is  changed 
from  time  to  time,  so  that  the  draught  through  changes 
its  direction,  and  different  parts  of  the  stack  are  exposed 
in  turn  to  the  heat.  The  point  to  be  kept  in  view  is  so 
to  regulate  the  quantity  of  air  which  comes  into  the  stack, 
that  there  shall  be  enough  air  to  burn  the  resinous 
matter  of  the  wood,  but  not  enough  to  burn  the  carbon 
of  the  wood  fibres.  These  wood  fibres  are  made  of  carbon 
and  water,  and  most  of  this  water  is  driven  off  as  steam. 

§  39.  Peat. — In  many  places  the  earth  is  too  damp  or 
poor  or  shallow  for  trees  and  shrubs  to  grow ;  then  the 
only  plants  found, are  mosses  and  rushes   and   stunted 


PEAT,  COAL-GAS.  49 

grass  and  such-like.  These  get  their  earth-food  from  the 
water  which  comes  down  from  other  places.  Their  dead 
remains  gradually  make  a  thicker  and  thicker  layer  year 
by  year,  until  in  some  places  it  is  as  much  as  forty  feet 
thick.  The  upper  part  of  such  a  peat  bed  or  bog  is  very 
much  like  the  plants  which  now  grow  on  it.  l!ut  the 
further  you  dig  down,  the  more  coaly  the  peat  becomes. 
This  peat  is  very  porous.  It  is  cut  out  with  a  spade,  and 
stacked  to  dry.  It  gives  out  less  heat  when  burning  than 
the  same  weight  of  coal  would  do.  Sometimes  such 
substance  is  called  "turf."  But  turf  is  properly  only  the 
uppe-r  layer  of  a  field  which  contains  the  roots  of  the 
living  plants  growing  on  it. 

§  40.  Coal-gas. — In  speaking  of  coal  and  coke,  I  said 
that  when  coal  was  heated  in  an  iron  box  having  a  small 
hole  in  it,  a  lot  of  gas  and  tar  came  out  of  the  hole. 
This  gas  is  crude  coal-gas,  and  is  the  gas  used  so  much 
for  lighting  streets  and  houses,  and  often  for  warming 
houses,  and  for  cooking.  The  gas  as  it  comes  from  the 
box  is  very  dirty,  and  has  to  be  cleaned  before  being  sent 
through  the  gas-pipes  to  the  burners.  Coal-gas,  even 
when  cleaned  to  the  utmost,  is  a  mixture  of  seven  or 
eight  kinds  of  gases.  The  chief  of  these,  in  quantity,  are 
hydrogen  and  a  gas  consisting  of  hydrogen  and  carbon, 
called  marsh-gas.  This  marsh-gas  is  also  found  in  coal- 
mines, and  is  then  called  fire-damp.  It  is  this  gas  which, 
when  mixed  with  the  air  in  the  mine,  takes  fire  when  a 
light  touches  it,  and  causes  dangerous  explosions.  Both 
hydrogen  and  marsh-gas  burn  in  the  air,  and  give  out 
great  heat,  but  scarcely  any  light.  In  one  hundred 
gallons  of  coal-gas,  as  it  generally  comes  from  the  burner, 
there  are  about  eighty  gallons  of  hydrogen  and  marsh-gas 
together,  and  about  thirteen  gallons  of  other  gases,  which 
either  do  not  burn,  or  do  not  give  light  when  burning. 
So  that  there  are  only  about  seven  gallons  of  gas  useful 
for  giving  light.  There  are  two  or  three  gases  in  the  coal- 
gas  which  have  this  property ;  they  are  all  compounds  of 


50  COAL-GAS,  CANDLES. 

hydrogen  and  carbon,  but  contain  a  larger  proportion  of 
carbon  than  marsh-gas  does.  The  impurities  which  are 
taken  away  from  the  crude  coal-gas  before  it  is  fit  for  use 
are  tar,  ammonia,  sulphide  of  hydrogen,  and  sulphide  of 
carbon.  Tar  is  a  solid,  and  is  made  of  carbon,  oxygen,  and 
hydrogen ;  to  get  rid  of  this,  the  gas  need  only  be  cooled. 
Ammonia  is  a  gas,  consisting  of  nitrogen  and  hydrogen  ; 
it  is  so  very  soluble  in  water,  that  the  coal-gas  need-  only 
be  passed  through  water  to  be  freed  from  it.  If  the  coal- 
gas  be  passed  amongst  an  acid  body,  the  ammonia  gets 
fixed.  The  coal-gas  is  sometimes  passed  among  the  acid 
phosphate  of  lime,  which  is  used  as  a  manure.  The 
ammonia  gets  fixed,  and  makes  the  manure  richer.  The 
sulphide  of  carbon  is  a  liquid  when  by  itself,  but  rises  as 
a  gas  in  large  quantities  in  gases  which  it  touches.  To  get 
rid  of  it,  the  coal-gas,  thus  cooled  and  washed,  is  passed 
over  quick-lime,  which  stops  the  bisulphide  of  carbon  and 
the  sulphide  of  hydrogen,  at  the  same  time  as  it  dries  the 
gas.  The  so  purified  gas  passes  through  tubes  into  large 
gas-holders,  and  from  them  into  the  mains  and  pipes  to 
the  gas-burners. 

Questions. — What  takes  place  when  wood  is  heated  in  a  still  ? 
What  comes  over  ?  What  is  left  hehind  ?  How  is  charcoal  usually 
made  ?  How  is  the  draught  of  a  charcoal-kiln  regulated  ?  What 
is  charcoal  made  of  ?  What  is  peat  ?  What  is  turi  ?  How 
is  coal-gas  made  ?  What  are  the  chief  gases  in  coal-gas  when  it 
comes  from  the  retorts  ?  How  is  it  cleaned  from  tar,  from 
ammonia,  from  bisulphide  of  carbon  ? 


XVII. 

Candles — Tallow,  Wax,  Spermaceti,  Stearine, 
Composite,  Paraffin. 
Things  to  be  Seen. — Tallow  candle — a  piece  of  honey- 
comb —  bees-wax  —  spermaceti  —  composite    candle — 
paraffin. 
§  41.   Candles — Tallow. — The  fat  of  sheep  and  kine, 
of  which  tallow  is  mainly  made,  is  contained  in  skins  so 


CANDLES — TALLOW,  WAX.  51 

small  that  you  need  a  microscope  to  see  them ;  and  to 
get  tlic  tallow  out  of  these  skins,  the  fat  is  heated  hy  itself 
in  a  pan,  so  as  not  to  burn  it.  The  skins  are  thus 
broken,  and  the  tallow  runs  together,  and  most  of  the 
broken  skins  rise  to  the  top  of  the  melted  tallow,  and  are 
skimmed  off.  Then  the  tallow  is  boiled  with  water, 
which  dissolves  out  the  dirt  and  takes  away  the  rest  of 
the  broken  skins.  The  tallow  is  then  ladled  off  from  the 
dirty  water  below  it,  and  allowed  to  cool  and  harden. 
"Dips"  are  made  by  taking  a  skein  of  cotton  (see  §  54), 
loosely  twisted,  to  form  the  wick,  and  dipping  it  into  the 
melted  tallow.  It  is  then  squeezed,  so  as  to  press  out  the 
air  in  it,  and  dipped  over  and  over  again,  the  tallow  on  it 
having  been  allowed  to  cool  and  harden  after  each 
dipping.  A  mixture  of  beef  fat  with  mutton  fat  makes  a 
harder  tallow  than  mutton  fat  alone ;  and  as  candles  made 
of  such  a  mixture  are  generally  cast  in  tubes,  they  are 
called  "moulds."  The  tubes  are  of  pewter  (a  mixture  of 
lead  and  tin,  see  §  82) ;  the  tube  stands  upright,  and  its 
bottom  has  the  shape  that  the  top  of  the  candle  is  to 
have,  there  being  a  little  hole  in  it  for  the  wick  to  pass 
through.  The  wick  is  stretched  down  the  centre  of 
ths  tube,  and  the  tallow  is  poured  in  and  allowed  to 
harden. 

The  wicks  of  most  cast,  that  is,  mould  candles,  are 
plaited  instead  of  being  twisted ;  the  effect  of  this  is,  that 
as  the  end  of  the  wick  burns,  it  curls  round  and  sticks  out 
of  the  flame,  and  so,  coming  into  better  contact  with  the 
air,  is  more  thoroughly  burnt  away.  Such  candles  need 
no  snuffing. 

§  42.  Wax. — Eees  gather  from  flowers  in  spring, 
summer,  and  autumn  their  winter  food ;  this  is  honey. 
They  store  it  up  in  cells  made  of  wax,  and  this  wax  is 
not  gathered  from  the  flowers,  but  is  made  hy  the  bee 
itself  out  of  a  part  of  the  honey.  The  honey  and  the 
wax  cells  form  the  honeycomb.  The  honey  having  been 
drained  and  pressed  out  of  the  comb,  the  wax  is  melted 


52  SPERMACETI,  STEARINE,  COMPOSITE,  PARAFFIN. 

and  stirred  with  hot  water,  to  free  it  from  the  rest  of  the 
honey  and  dirt.  "When  cold  and  hard,  it  is  cut  into  thin 
shavings  and  exposed  to  sunshine  and  air ;  this  whitens 
it,  and  it  can  then  be  made  into  candles  in  the  same  way 
as  mould  candles  are  made. 

§  43.  Spermaceti. — Spermaceti,  of  which  candles  are 
sometimes  made,  is  found  in  the  head  of  a  kind  of  Whale. 
When  the  animal  is  alive  and  warm,  the  spermaceti  is 
liquid,  being  dissolved  in  an  oil  called  sperm  oil.  On 
cooling,  after  death,  much  of  the  spermaceti  separates 
from  the  oil ;  it  is  strained  and  pressed,  and  boiled  with 
wood  ashes,  which  further  cleans  it  from  the  oil.  Candles 
are  cast  from  it  as  from  wax  and  tallow. 

§  44.  Stearine. — There  are  two  different  things  called 
stearine,  and  candles  are  made  out  of  both  of  them.  True 
stearine  is  a  hard  fat  which  forms  a  part  of  tallow,  cocoa- 
nut  oil,  palm  oil,  and  many  other  oils  and  fats.  This  fat 
contains  Glycerine.  If  the  glycerine  is  separated  from 
it,  it  is  still  called  stearine ;  but  it  ought  rather  to  be 
called  stearic  acid.  To  get  this  stearic  acid,  or  stearine, 
from  the  true  stearine  fat,  the  fat  is  heated  with  water 
and  lime,  by  which  means  a  kind  of  lime  soap  (see  §  119) 
is  formed.  On  warming  this  soap  with  almost  any  strong 
acid,  the  stearic  acid  is  got.  Another  way  is  to  heat  the 
tallow  or  other  fat  very  hot  in  a  still,  and  blow  steam  into 
the  fat.  In  the  vessel  which  catches  the  things  which 
come  from  the  still,  a  solid  cake  containing  stearic  acid  is 
found.  If  this  is  melted,  and  allowed  to  partly  solidify 
in  cooling,  and  then  pressed,  the  other  things  beside  the 
stearic  acid  are  pressed  out,  and  the  solid  stearic  acid, 
called  stearine,  is  left. 

Composite  candles  are  made  by  mixing  tallow  and 
stearine  in  different  proportions. 

§  45.  Paraffin. — In  some  places  a  rock  is  found  which 
can  be  split  like  slate  into  sheets,  and  which  holds  a  large 
quantity  of  tarry  matter ;  its  tarry  matter  has  probably 
got  into  it  by  neighbouring  coal  having  been  heated  by 


PARAFFIN,  OILS.  53 

the  natural  heat  of  the  earth  along  with  the  rock.  Such 
rocks  are  called  bituminous  shales.  When  they  are 
heated  in  a  vessel  like  a  gas-retort,  they  lirst  give  off 
a  colourless  oil  called  paraffin  oil,  and  then  a  tarry 
matter,  which  is  of  a  deep  brown  colour;  from  this  tarry 
matter  solid  paraffin  separates  on  cooling.  It  is  collected 
in  canvas  bags,  and  squeezed  as  dry  as  possible.  To 
purify  it,  it  is  dissolved  over  and  over  again  in  the 
colourless  paraffin  oil  which  came  over  when  the  shale 
was  first  heated,  and  most  of  this  being  distilled  off, 
the  paraffin  is  allowed  to  solidify  out ;  or  it  is  boiled 
with  oil  of  vitriol  (see  §  127),  and  then  with  soda  (see 
§  120),  and  then  with  charred  bones;  this  purifies  it  and 
makes  it  white.  When  candles  are  made  out  of  paraffin, 
the  paraffin  is  usually  mixed  with  a  little  stearine. 

Questions. — How  is  tallow  got  from  fat  ?  How  are  dips  made  ? 
How  are  mould  candles  made?  What  is  the  use  of  plaiting  the 
wick  of  a  candle  ?  How  is  bees-wax  made  ?  How  is  it  cleaned  ? 
How  is  it  whitened  ?  Where  is  spermaceti  found  ?  How  is  it 
cleaned  from  sperm  oil  ?  How  is  it  further  cleaned  ?  What  is 
stearine,  and  where  is  it  found  ?  What  is  the  difference  between 
true  stearine  and  stearic  acid  ?  In  what  ways  are  stearic  acid  and 
glycerine  got  from  fat?  What  are  composite  candles  made  of? 
Where  is  paraffin  found  ?  What  is  bituminous  shale  ?  How  is 
solid  paraffin  got  from  it  ?     How  is  solid  paraffin  cleaned  ? 


XVIII. 

Oils— Mineral  Oils,  Animal  Oils,  Vegetable  Oils. 

Things  to  be  Seen — Some  petroleum,  train  oil,  colza  oil, 
and  olive  oil — sulphur — iron-pyrites — the  sulphides  of 
other  metals,  as  many  as  can  he  got. 

§  46.  Oils — Petroleum. — As  stated  above,  paraffin  oil 
is  the  oil  which  first  comes  from  the  still  or  retort  when 
bituminous  shale  is  heated.  Such  heating  often  takes 
place  in  the  earth  itself,  and  the  oil  is  found  in  the  porous 
rocks  themselves.  Then  we  have  only  to  dig  wells,  and 
the   oil  collects   in   them,   like   water   in   a  water-well. 


54  OILS,  MATCHES,  SULPHUR. 

Where  it  is  thus  found  in  nature,  it  is  called,  generally, 
petroleum.  The  crude  paraffin  is  often  re-distilled,  and 
the  part  which  first  comes  over  is  kept  separate  from  that 
which  comes  over  last.  The  first  is  useful  where  one 
wants  a  liquid  which  dries  up  quickly,  but  it  is  dangerous 
to  use  in  lamps,  because  it  mixes  as  a  gas  with  the  air, 
and  the  mixture  easily  catches  fire ;  the  second  is  safer. 

§  47.  Animal  Oils— Train  Oil. — The  fat  of  whales, 
which  is  called  blubber,  is  cut  into  pieces  and  put  into 
casks ;  after  a  time  the  little  skins  which  hold  the  oil 
break  and  rot.  The  stuff  is  then  heated  and  drained,  and 
the  oil  which  drains  off  is  called  train  oil.  Seal  Oil  and 
Porpoise  Oil  are  got  from  these  animals  in  the  same  way. 
Sperm  Oil  is  the  oil  which  is  pressed  from  the  spermaceti 
(see  §  43). 

§  48.  Vegetable  Oils. — Most  seeds  contain  oils ;  those 
most  used  for  giving  light  are  Colza  Oil,  Cocoa-nut  Oil, 
and  Olive  Oil.  The  colza  is  a  kind  of  cabbage.  Its 
seeds,  when  pressed,  give  out  their  oil.  Cocoa-nut  oil  is 
used  for  lighting  in  the  hot  countries  where  the  cocoa-nut 
grows,  for  such  countries  are  so  hot  that  there  the  oil  is 
generally  liquid.  But  in  colder  countries  it  becomes  a 
soft  solid,  like  butter,  and  is  too  soft  for  candles,  but 
not  liquid  enough  for  lamps.  Olive  oil  is  not  much  used 
in  this  country  for  lighting ;  neither  it  nor  cocoa-nut 
oil  give  anything  like  so  bright  a  flame  as  colza  oil. 

§  49.  Matches. — To  understand  how  matches  are 
made,  and  how  they  light,  it  is  well  to  understand  first 
what  are  sulphur  (brimstone),  phosphorus,  and  nitre 
(saltpetre). 

Sulphur,  or  brimstone,  is  an  element ;  it  is  found  by 
itself  in  large  quantities  in  Sicily  and  Iceland,  and  other 
countries  where  there  are  or  have  been  volcanoes.  To  free 
such  sulphur  from  the  rocks  with  which  it  is  mixed,  the 
rock  containing  the  sulphur  is  heated  in  an  earthenware  pot 
having  a  wide  tube  bent  down  and  dipping  under  water. 
On  heating  the  pot,  the  sulphur  melts  and  distils  over, 


suLruun,  ruosrnoRus,  nitre,  saltpetre.  55 

and  is  cooled  and  solidified  by  the  water.  It  is  then 
melted  and  cast  in  moulds,  and  we  get  it  so  as  stick-sulphur  j 
or  it  is  again  melted  and  distilled  in  a  large,  cool  room. 
It  settles  on  the  walls  and  on  cloths  hung  up  in  the, 
room  as  a  fine  powder.  This  is  collected  and  sold  as 
Hour  of  sulphur  (called  also  flowers  of  sulphur).  Sulphur, 
when  heated  in  the  air,  burns  (that  is,  it  is  oxidised)  with 
a  blue  flame,  and  gives  rise  to  a  suffocating  gas  called 
sulphurous  acid.  This  gas  is  sulphur  not  fully  oxidised. 
The  gas  can  be  made  to  unite,  in  the  presence  of  water, 
with  half  as  much  again  of  oxygen,  and  becomes  then  (in 
union  with  water)  oil  of  vitriol  or  sulphuric  acid  (see 
§  137).  Metals  united  with  sulphur  are  called  sulphides 
or  pyrites. 

Impure  sulphur  is  also  got  from  iron-pyrites  (sulphide 
of  iron),  which,  on  being  heated,  gives  up  half  its 
sulphur.  This  is  impure,  because  it  almost  always 
contains  arsenic. 

Questions. — How  is  petroleum  made  in  the  earth  ?  What  13 
done  to  natural  petroleum  so  as  to  separate  the  drying  from  the 
not-drying  part  ?  What  is  train  oil  got  from,  and  how  is  it  got  ? 
From  what  animals  is  train  oil  got  ?  What  is  sperm  oil  ?  What 
are  colza  oil,  cocoa-nut  oil,  olive  oil?  What  is  sulphur  or  brim- 
stone ?  Where  is  it  found  ?  How  is  stick-sulphur  got  ?  How  is 
flour  of  sulphur  got  ?  What  happens  to  sulphur  when  it  burns  ? 
What  acid  is  made  by  further  burning  sulphur  ?  What  name 
is  given  to  metals  united  with  sulphur  ?  From  what  other  body  is 
sulphur  got ! 


XIX. 

Matches,  Phosphorus,  Nitre,  Nitrate  of  Soda, 
Chlorate  of  Potash. 

Things  to  be  Seen. — Some  phosphorus  in  water  in  a 
bottle — some  bone-ash,  charcoal,  nitre,  nitrate  of  soda, 
chloride  of  potassium,  chlorate  of  potash,  gum  arable, 
paraffin,  litharge,  glass  powder — some  red  phosphorus. 

§  50.  Phosphorus,  Nitre,  Saltpetre. — Phosphorus 
is  an  element,  but  is  never  found  by  itself    in  nature, 


56  PHOSPHORUS,  NITRE,  SALTPETRE. 

because  it  oxidises  very  readily,  and,  indeed,  often  takes 
fire  by  itself  when  exposed  to  the  air.  It  is  got  from  the 
ashes  of  bones,  in  which  it  exists  in  union  with  oxygen 
(forming  phosphoric  acid)  and  lime,  forming  altogether  a 
body  called  the  phosphate  of  lime.  The  rest  of  the  bone- 
ash  is  almost  wholly  carbonate  of  lime.  This  bone-ash  is 
mixed  with  water  and  sulphuric  acid  (see  §  127).  The 
sulphuric  acid  takes  the  lime  from  both  the  carbonate 
and  the  phosphate,  forming  in  both  cases  the  insoluble 
body  sulphate  of  lime  (plaster  of  Paris,  gypsum,  §  12). 
The  carbonic  acid  rises  as  bubbles,  and  escapes ;  the  phos- 
phoric acid  remains  in  solution,  and  is  poured  off  from  the 
gypsum.  It  is  then  heated,  to  drive  off  most  of  the 
water,  until  it  becomes  thick;  then  it  is  mixed  with 
charcoal  powder  and  heated  in  an  earthenware  pot 
having  a  copper  tube  dipping  under  water.  The  carbon 
takes  away  the  oxygen  from  the  phosphoric  acid  and 
passes  off  as  a  gas  (carbonic  acid).  The  phosphorus  thus 
left  alone  distils  over  and  falls  through  the  water ;  it  is 
cleaned  by  being  pressed  under  water  through  a  bag  of 
wash-leather,  and  must  be  always  kept  under  water.  It 
is  a  dangerous  thing  to  make,  and  dangerous  to  touch, 
because  it  catches  fire  if  warmed  by  the  hand  in  the  air, 
and  the  burns  it  makes  are  very  difficult  to  heal.  Phos- 
phorus is,  when  pure,  transparent  and  colourless,  and  is 
as  soft  as  wax.  If  it  be  dried  and  heated  for  some  time 
by  itself,  shut  off  from  the  air,  it  becomes  hard  and  red, 
and  difficult  to  melt,  and  much  more  difficult  than  before 
to  burn.  It  is  then  called  red  phosphorus,  or  amorphous 
.phosphorus. 

Nitre  (saltpetre,  nitrate  of  potash).  —  Animal  and 
vegetable  matter  containing  nitrogen,  when  mixed  with 
earth  and  slaked  lime  and  carbonate  of  potash,  and 
exposed  for  some  weeks  to  moist  air,  has  its  nitrogen 
oxidised  to  nitric  acid,  which  unites  with  the  potash  and 
lime,  forming  nitrates  of  potash  and  nitrates  of  lime. 
Both  of  these  can  be  dissolved  by  water,  and  on  adding 


NITRE,  CHLORATE    OF    POTASSIUM,  MATCHES.  57 

more  carbonate  of  potash  to  the  solution,  all  the  lime  is 
made  insoluble  as  carbonate  of  lime,  while  the  whole  of 
the  nitric  acid  is  now  united  with  potash,  and  can  be  got 
pure  by  driving  off  the  water  by  heat.  It  is  then  called 
nitre,  or  saltpetre;  or,  if  it  has  been  melted,  whereby  it  is 
by  no  means  altered,  it  is  called  sal-prunella.  Nitre  is 
made  of  nitrogen,  oxygen,  and  the  metal  potassium.  In 
parts  of  South  America  where  no  rain  falls,  the  ground  is 
covered  with  Nitrate  op  Soda,  called  also,  from  the 
shape  of  its  crystals,  cubic  nitre.  If  this  be  dissolved 
and  mixed  with  a  solution  of  chloride  of  potassium, 
common  salt  (which  is  chloride  of  sodium)  is  formed,  and 
nitrate  of  potassium.  The  latter  is  more  soluble  than  the 
former  in  hot  water,  so  that,  on  boiling  off  the  water 
from  the  mixture,  the  common  salt  can  be  scooped  out  as 
it  is  separated.  The  chloride  of  potassium  which  is  used 
for  this  purpose  is  sometimes  found  as  a  mineral  by  itself, 
and  sometimes  united  with  chloride  of  magnesium,  which 
latter,  being  far  more  soluable  in  water,  can  be  dissolved 
out.  Nitrate  of  potash,  or  nitre,  contains  a  very  large 
quantity  of  oxygen,  which  it  readily  gives  up  when  heated, 
and  so  is  used  to  oxidise  bodies. 

§  51.  Chlorate  of  Potassium. — This  body,  which 
is  used  in  making  matches,  is  very  like  nitre  in  most  of 
its  properties.  It  would  take  too  long  to  describe  how 
it  is  made.  It  is  made  of  chlorine,  oxygen,  and 
potassium. 

§  52.  Matches,  or  lucifer  matches,  or  lucifers,  as  they 
are  called,  are  now  made  chiefly  of  three  kinds— those 
which  have  sulphur  in  them  (these  are  mostly  foreign) ; 
those  which  are  without  sulphur,  and  light  when  rubbed 
on  anything  which  is  rough  and  dry  ;  and  those  which 
light  easily  only  when  rubbed  on  a  particular  surface — 
the  last  kind  are  called  safety-matches.  Sulphur  matches 
are  made  by  dipping  the  ends  of  splinters  of  wood  into 
sulphur,  and  then  into  a  paste  of  phosphorus,  gum 
arabic  (see  §  139),  and  water,  and  some  colour,  such  as 


58  MATCHES,  THE   LIGHTING    OF   A   MATCH. 

Prussian  blue  (see  §§  62,  126) ;  the  matches  are  then 
dried. 

Ordinary  matches  without  sulphur  are  made  by  slightly 
charring  the  end  of  the  wood,  then  dipping  it  into  melted 
paraffin  (see  §  45),  and  then  into  a  paste  of  phosphorus 
(see  §  50),  nitre  (see  §  50),  melted  glue  (see  §  25),  and  an 
oxide  of  lead,  and  some  powdered  glass  stained  variously. 

Matches  which  only  light  easily  on  a  prepared  surface 
are  made  as  in  the  above  paragraph,  with  the  exception 
that  the  paste  contains  no  phosphorus,  but  sulphur, 
united  with  antimony  and  some  chlorate  of  potash.  The 
phosphorus,  instead  of  being  as  ordinary  phosphorus  on 
the  match,  is  finely  powdered  red  phosphorus  (see  §  50) 
mixed  with  fine  sand,  and  stuck  by  means  of  glue  on 
paper,  which  is  generally  pasted  on  the  match-box. 

Questions. — What  is  bone-ash  ?  "What  happens  when  bone-ash 
and  sulphuric  acid  are  mixed  together  ?  How  is  phosphorus  got 
from  phosphoric  acid  ?  What  is  phosphorus  like  ?  How  is  red  or 
amorphous  phosphorus  made  ?  How  is  nitre  made  ?  What  is  it 
made  of?  Where  is  nitrate  of  sodium  found  ?  How  is  nitrate  of 
sodium  used  to  make  nitre  ?  What  elements  are  there  in 
chlorate  of  potash?  How  are  sulphur  matches  made?  How  are 
those  matches  made  which  have  no  sulphur,  and  which  light  when 
rubbed  on  anything  rough?  How  are  those  matches  made  which 
only  light  easily  on  certain  surfaces?  What  are  those  surfaces 
covered  with  ? 


XX. 

Lighting  a  Match,  or  Striking  a  Light. 

Things  to  be  Seen. — A  flint  and  steel — a  dean  plate — 

a  pinch  of  gunpowder — a  magnet — a  splinter  of  wood 

tipped  ivith  sulphur — some  German  tinder — as  many 

different  lands  of  matches  as  can  be  get — "  Safety  " 

matches. 

§  53.  The  lighting  of  a  match,  or  striking  a  light. 

— If  you  hit  a  piece  of  steel  upon  a  flint-stone  you  get 

sparks,  and  if  you  do  so  over  a  clean  plate,  you  will  see 

that  where  the  sparks  have  fallen  there  are  little  black 


STRIKING    A    LIGIIT.  59 

specks,  which  will  cling  to  a  magnet.  These  are  an  oxide 
of  iron.  The  blow  has  done  two  things  :  it  has  torn  oil'  a 
little  piece  of  the  iron,  and  it  has  heated  that  little  piece 
so  hot  that  it  burns  in  the  air — that  is,  oxidises.  Such 
sparks  will  set  fire  to  gunpowder,  and  formerly  guns  were 
fired  by  means  of  flint-locks — that  is,  flints  fastened  to  a 
bent  spring,  and  which,  on  the  spring  being  let  go,  struck 
against  a  piece  of  steel,  the  spark  so  made  being  thrown 
upon  a  pinch  of  gunpowder  in  the  "  pan,"  a  shallow  hollow 
outside  the  barrel,  but  leading  into  it  through  the  "  touch- 
hole."  Such  sparks  will  also  set  fire  to  rag-charcoal,  called 
tinder,  or  to  the  dry  fungus  called  German  tinder.  These 
substances  do  not  burn  with  a  flame,  but  smoulder.  On 
blowing,  this  smouldering  increases;  and  then,  if  a 
splinter  of  wood  tipped  with  sulphur  is  made  to  touch 
the  burning  tinder,  the  sulphur  catches  fire  and  sets  lire 
to  the  wood ;  and  this  used  to  be  the  way  (which  is  still 
sometimes  used)  for  getting  a  light.  The  cause  of  light, 
observe,  was  the  blow.  You  have  also  noticed  that  when 
you  rub  two  things  together  they  get  hot,  and  the  harder 
you  work  the  hotter  they  get ;  in  fact,  if  you  set  yourself 
to  do  such  a  piece  of  work  as  pushing  a  wheelbarrow  up 
a  hill,  you  know  it  is  harder  to  do  this  job  when  the  axle 
is  dry  than  when  it  is  greased ;  you  also  know  that  if  the 
axle  is  dry  you  find  it  hot  at  the  end  of  the  task.  When 
you  have  got  the  wheelbarrow  to  the  top,  you  are  more 
tired  if  the  axle  is  dry  than  if  it  is  greased  ;  you  have 
done  more  work  than  you  bargained  for.  You  have  not 
only  done  the  work  you  set  yourself,  but  you  have  heated 
the  axle.  So  whenever  you  spend  work  on  rubbing  two 
things  together,  you  make  the  things  hot.  Friction 
always  makes  things  hot.  It  is  thus  when  the  end  of  a 
match  is  rubbed  on  a  rough  surface  :  the  phosphorus, 
which  is  covered  with  gum  or  glue,  is  laid  bare  and 
heated;  it  catches  fire,  and  immediately  takes  oxygen  not 
only  from  the  air,  but  from  the  nitre  or  chlorate  of  potash, 
which  is  touching  it  on  the  match's  end.     Its  burning  is 


60  THE   LIGHTING   OF   A   MATCH. 

thus  helped ;  the  whole  gets  hot  enough  to  set  fire  to 
the  sulphur  or  paraffin  which  is  next  to  the  wood,  and  so 
to  the  wood  itself. 

In  safety-matches,  where  the  phosphorus  (see  §  50). 
mixed  with  sand,  is  on  a  paper  by  itself,  the  heat 
of  rubbing  sets  fire  to  a  very  small  patch  indeed  of 
the  phosphorus ;  but  small  as  this  is,  the  heat  of  its 
burning  is  enough  to  make  the  sulphur  on  the  match-end 
take  oxygen  from  the  chlorate  of  potash  there,  and  burn 
and  set  fire  to  the  wood. 

Questions. — What  happens  when  you  hit  a  piece  of  steel  with  a 
flint  ?  What  are  the  sparks  so  got  ?  How  can  such  sparks  be 
used  for  getting  a  light  ?  What  happens  when  you  rub  any  two 
things  together  ?  What  becomes  of  the  extra  work  you  have  to  do 
when  part  of  your  work  is  lost  by  friction  ?  How  does  a  common 
match  catch  fire  when  rubbed  ?  How  are  safety-matches  made 
and  used  ? 


PART    V. 

FINISHING  AND  FURNISHING-. 

XXI. 

Cotton  Wadding,  Thread,  Warp,  Woof,  Muslin, 
Flax,  Linen,  Tow,  Hemp. 

Tuings  to  be  Seen. — Some  cotton-wool — either  a  pod  of 
cotton-wool  or  a  drawing  of  one — wadding — cotton 
yarn — cotton-thread — calico — muslin — some  linseed — 
either  a  flax-plant  or  a  drawing  of  one — some  linen — 
some  tow — canvas — either  a  hemp-plant  or  a  drawing 
of  one — cords  or  ropes  of  hemfi£—a  drawing  of  a  loom. 

§  54.  Cotton,  Calico,  Muslin. — In  the  southern 
parts  of  North  America,  in  India,  in  Egypt,  and  other  hot 
countries,  a  plant  grows  called  the  cotton-plant,  which  is 
a  kind  of  mallow.  But  the  fruit  of  this  plant,  when  ripe, 
is  a  thin  hard  shell  containing  cotton-wool,  and  amongst 
this  wool  are  the  true  seed.  If  you  liken  the  cotton- 
fruit  to  an  orange,  the  haid  skin  is  to  be  likened  to 
the  soft  skin  of  the  orange,  the  cotton-wool  to  the 
pulp  which  we  eat,  and  the  cotton-seed  to  the  orange- 
pips.  The  wool  is  picked  out  from  the  hard  shell,  and 
the  seeds  are  torn  from  the  wool  by  a  machine  called 
a  gin,  which  is  a  sort  of  round  saw,  the  teeth  of  which 
drag  the  cotton  away  from  the  seed.  "Wadding  is  the 
form  in  which  cotton-wool  is  often  sold.  It  is  made  by 
covering  the  two  sides  of  a  layer  of  cotton-wool  with  thin 
glue  or  size.  Cotton-thread. — The  cotton-wool  is  next 
carded — that  is,  combed — so  that  all  the  fibres  lie  side  by 


62  COTTON,  CALICO,  MUSLIN. 

side,  and  not  across  one  another  in  a  tangle.  It  is  then  drawn 
together,  and  slightly  twisted,  and  wound  on  reels ;  from 
these  it  is  again  reeled  off  and  twisted,  and  so  forms 
cotton-thread.  Cotton-thread  for  sewing  is  made  by 
twisting  a  few  of  these  threads  together.  Cotton-cloth, 
or  calico,  is  made  by  stretching  a  number  of  such  threads 
side  by  side  till  they  form  a  sheet  as  wide  as  the  cloth  is 
to  be.  These  form  the  Warp.  Then  a  thread  is  passed 
backwards  and  forwards  across  them,  over  the  first,  under 
the  second,  over  the  third,  and  so  on  to  the  last.  Suppose 
it  goes  over  the  last,  it  comes  round,  turning  under  the 
last,  over  last  but  one,  and  so  on  till  it  comes  back 
to  the  first.  It  goes  under  this,  turns  round,  and  goes 
on  again  as  it  did  at  starting.  This  thread  which  goes 
backwards  and  forwards  forms  the  Woof.  The  woof  thread 
is  carried  backwards  and  forwards  on  a  reel  with  pointed 
ends  called  a  Shuttle.  Instead  of  making  the  shuttle 
move  up  and  down  as  it  threads  its  way  from  one  side  of 
the  warp  to  the  other,  it  may  go  straight,  if,  when  it  is 
going  one  way,  the  second,  fourth,  sixth,  and  so  on, 
threads  of  the  warp  are  raised ;  for  then  the  shuttle  goes 
under  all  these,  while  it  goes  over  the  first,  third,  and  so 
on.  When  it  is  coming  back,  the  second,  fourth,  sixth 
warp  threads  are  lowered,  and  the  first,  third,  fifth,  and  so 
on  are  raised,  so  that  now  it  passes  over  the  first  lot  and 
under  the  second  lot.  The  warp  threads  are  upon  a  very 
large  reel,  and  each  thread,  just  in  front  of  the  path 
of  the  shuttle,  passes  through  a  noose  of  varnished  (see 
§  67)  worsted  (see  §  70)  yarn.  These  nooses  are  so  fixed, 
that  while  the  one  half  of  them — say  those  through  which 
the  second,  fourth,  sixth,  and  so  on  threads  of  the  warp 
pass — are  raised,  the  other  half — namely,  those  through 
which  the  first,  third,  fifth,  and  so  on  threads  pass — are 
lowered.  Then  the  shuttle  passes  ;  then  the  first  set  are 
lowered  and  the  second  raised,  and  the  shuttle  passes 
back.  The  web  of  calico — that  is,  the  sheet  already 
made — is  pulled  a  little  way  from  the  reel  as  the  wool 


FLAX — LINEN.  63 

thread  goes  backwards  and  forwards,  so  as  to  pull  a 
little  more  warp-thread  off  it.  By  this  means  ?  con- 
tinuous piece  of  calico  many  yards  long  is  woven  on  a 
machine  or  loom  only  a  few  feet  long.  Muslin  is  a  line 
cotton. 

§  55.  Flax — Linen. — The  flax-plant  is  a  plant  which 
dies  after  it  has  borne  seed ;  and  this  it  does  only  once  a- 
year,  so  it  is  called  an  annual.  The  seed  of  flax  is 
linseed,  aud  this  seed  contains  the  oil  called  linseed  oil 
(see  §  59).  When  the  plants  have  done  growing,  they 
are  about  three  feet  high.  They  are  then  pulled  up  by 
the  roots,  and  sometimes  piled  together  lightly,  so  that 
the  sun  and  air  can  get  at  them  and  dry  them.  In  some 
countries  this  drying  does  not  take  place.  Whether  dried 
or  not,  the  seed  is  beaten  out,  and  the  stems  are  steeped 
in  water  for  a  week  or  longer  :  the  warmer  the  water  the 
shorter  is  the  time  needed.  {Soft  water  (see  §  33)  is  the  best. 
The  flax  stem  contains  long  threads  or  fibres,  and  these 
are  the  useful  part  of  the  plant ;  these  fibres  surround 
the  woody  part  of  the  stem.  Neither  the  woody  part 
nor  the  resin  which  is  in  it  are  of  any  use  in  making 
linen.  The  soaking  in  the  water  rots  the  woody  part  and 
makes  it  brittle,  but  it  does  not  injure  the  fibre.  The 
soaked  flax  is  next  dried,  either  in  the  air  or  in  drying- 
rooms.  To  get  rid  of  the  rotted  wood  and  the  resin, 
which  have  become  brittle,  the  flax  is  next  well  beaten, 
rubbed,  and  bent  about  by  blows  with  wooden  hammers,  or 
by  passing  it  between  rollers.  The  wood  and  resin,  and 
some  of  the  shorter  fibres,  are  beaten  out,  while  the  best, 
that  is,  the  longest,  fibres  remain  together.  The  shorter 
fibres  are  shaken  and  combed  as  free  as  possible  from  the 
dirt,  and  form  what  is  called  Tow.  Such  tow  is  very 
coarse,  and  is  used  for  making  such  things  as  sacks.  The 
longer  fibres  are  next  combed,  which  again  takes  out  the 
shorter  fibres  and  bundles  of  fibres  which  are  still  sticking 
together.  This  is  a  finer  tow  than  the  first,  and  when 
woven  it  is  called  Canvas.     It  is  used  for  tents,  sails,  and 


64  HEMP,  PAPER. 

euch  things.  But  the  web  which  is  made  from  hemp, 
which  is  a  different  plant,  is  also  called  canvas  (see  §  56). 
The  spinning  of  the  flax  into  threads,  and  the  weaving  of 
linen  from  it,  are  so  like  the  spinning  and  weaving  of 
cotton,  that  I  need  say  nothing  about  them  (see  §  54). 

§  56.  Hemp. — The  plant  of  which  hemp  is  made  is 
not  much  grown  in  this  country.  Most  of  the  hemp  used 
is  brought  from  Russia,  Italy,  and  the  East  Indian 
Islands.  It  is  made  from  the  plant,  which  grows  five  or 
six  feet  high,  much  as  flax  is  made  from  the  flax-plant. 
The  fibre  of  hemp  is  coarser  and  stronger  than  that  of 
flax.  It  is  used  for  rough  towels,  and  especially  for 
cords,  ropes,  and  ship's  cables ;  for  it  does  not  rot  in  the 
water. 

Questions. — Where  does  the  cotton-plant  grow  ?  What  part  of 
the  plant  is  the  cotton  ?  How  is  the  cotton-wool  freed  from  tlie 
seed  ?  How  is  wadding  made  ?  What  does  carding  do  to  the 
wool  ?  How  is  cotton-thread  made  from  carded  wool  ?  What  is 
the  warp?  What  is  the  woof?  How  is  the  woof-thread  woven 
into  the  warp  ?  What  is  linen  made  from  ?  What  is  the  seed  of 
flax  ?  What  is  done  to  the  flax-plant  to  get  the  fibres  clean  ? 
What  is  tow,  and  what  is  it  used  for  ?  What  is  hemp,  and  what  is 
it  used  for  ? 


XXII. 
Paper. 

Things  to  be  Seent. — Calico — linen — straw — wood — 
hemp — tow — esparto  — soda — slaked  lime — chloride  of 
lime — pieces  of  felt — blotting  paper — size — drawing  of 
a  'paper  mill — resin — alum. 

§  57.  Paper. — A  piece  of  paper  is  a  sheet  of  fibres 
matted  together ;  and  paper  can  be  made  out  of  almost 
anything  which  has  fibres.  It  is  generally  made  out  of 
cotton,  linen,  straw,  wood,  hemp,  or  tow,  or  the  stalk  of  a 
sedge  called  Esparto,  which  grows  in  Spain  and  North 
Africa.  When  made  out  of  cotton  or  linen,  rags  of  these 
substances  are  generally  used,  because  they  are  cheaper. 


PAPER.  65 

The  dry  rags  are  cleaned  first  by  hand.  Pins  and 
buttons  and  such  things  are  taken  off'.  The  seams  are 
undone,  and  the  rags  are  cut  into  small  pieces  and  sorted. 
Then  they  are  rubbed  together  upon  a  metal  sieve,  which 
frees  them  from  dust.  Next  they  are  boiled  with  water, 
to  which  is  added  some  soda  (see  §  120)  and  slaked  lime 
(see  §  3).  This  takes  out  grease  and  must  stains.  After 
being  washed,  they  are  torn  to  pieces  by  being  brought 
between  two  sets  of  steel  teeth,  something  like  saw  teeth. 
One  of  these  sets  is  on  a  wheel  which  is  driven  round. 
Then,  if  necessary,  the  rags  are  bleached — that  is,  made 
as  white  as  they  can  be.  This  is  done  by  mixing  them 
with  water  containing  some  chloride  of  lime  (see  §  131). 
After  being  again  washed,  they  are  further  torn  to  pieces  in 
water  by  an  engine  with  saw  teeth  like  the  first  one,  only 
the  teeth  are  finer,  and  the  two  faces  which  carry  the 
teeth  are  nearer  together.  This  grinds  the  rags  into  a 
pulp.  The  fibres  are  broken  very  short ;  all  this  is  done 
by  engines.  The  paper  is  made  from  the  pulp,  sometimes 
by  hand  and  sometimes  by  machinery.  Let  us  suppose 
it  is  to  be  made  by  hand.  The  pulp  is  kept  well 
stirred  up  in  a  vat ;  into  this  a  sieve  is  dipped  and 
brought  up  again,  care  being  taken  not  to  tilt  it ;  the 
water  drains  through  the  sieve  and  leaves  a  sheet  of  pulp, 
and  this  is  helped  by  gently  shaking  the  sieve.  The 
sieves  used  in  paper-making  are  made  of  brass  wire ; 
these  are  stretched  in  a  frame  side  by  side,  close  to  one 
another,  and  there  are  a  few  cross  wires  to  support  the 
others.  This  frame  is  surrounded  by  an  edge  or  rim, 
which  can  be  taken  off.  The  thickness  of  the  paper,  it  is 
clear,  is  greater  the  deeper  this  rim  is,  and  of  course,  also, 
the  thicker  the  pulp  is — that  is,  the  less  water  there  is  in 
it.  When  the  water  is  drained  off",  the  rim  is  taken  off 
the  fiame,  and  this  is  turned  over  on  a  piece  of  felt  (see 
§  87),  whereby  the  pulp  which  was  on  the  frame  is  left  on 
the  felt ;  another  piece  of  felt  is  now  put  over  the  paper, 
then  another  sheet  of  the  paper,  then  another  piece  of 


66  PAPER. 

felt,  and  so  on.  The  pile  made  in  this  way  is  strongly 
pressed,  so  as  to  squeeze  out  as  much  water  as  possible. 
Then  the  sheets  are  taken  out  from  between  the  felts  and 
dried.  In  this  state  the  paper  is  blotting-paper.  Writing- 
ink  soaks  and  spreads  in  it,  and  so  it  cannot  be  used  for 
writing  on.  To  give  it  the  power  of  keeping  the  ink  in  one 
place,  it  is  dipped  in  clean  white  size  (see  §  ^5),  and  again 
pressed  and  dried.  The  surface  is  now  rough.  If  it  be 
wanted  smooth,  the  sheet  is  put  between  two  very  smooth 
sheets  of  copper,  and  the  whole  three  are  passed  between 
two  heavy  metal  cylinders,  with  scarcely  enough  space 
between  them  to  let  the  copper  plates  and  paper  pass. 
After  two  or  three  passages  through  the  rollers,  the  paper 
is  found  to  have  a  very  smooth  surface,  which  makes  it 
easier  to  write  on.  By  far  the  larger  quantity  of  paper  is 
made  from  the  pulp  by  machinery.  The  things  which 
the  machine  does  to  the  pulp  are  like  those  done  when 
the  paper  is  made  by  hand ;  but  the  work  goes  on  at 
a  greater  rate.  The  pulp  is  let  flow  over  the  edge  of  a 
trough  as  wide  as  the  paper  is  to  be,  and  let  fall  upon  a 
wire  cloth,  the  two  end  edges  of  which  are  joined 
together.  This  wire  cloth,  in  the  shape  of  a  jack-towel, 
passes  round  two  rollers  at  the  same  height  from  the 
ground,  so  that  when  these  rollers  turn  round,  the 
upper  half  of  the  wire  cloth  moves  away  from  the  falling 
pulp.  Ey  this  means,  as  the  water  drains  off,  a  continuous 
sheet  of  partly  dry  pulp  is  carried  along.  Moving  straps 
at  the  side  stop  the  pulp  from  flowing  over,  and  the  wire 
sieve  jerks  a  little  sideways  to  help  the  water  to  run 
through.  In  order  to  get  rid  of  still  more  of  the  water, 
the  wire  web  carrying  the  pulp  is  made  to  pass  closely 
over  some  boxes  without  tops,  and  the  air  being  drawn 
from  these  boxes,  the  water  from  the  pulp  follows  it. 
The  sheet,  thus  well  drained,  is  next  passed  between  two 
rollers  (like  mangle-rollers)  covered  with  felt.  Then  it  is 
carried  along  on  a  broad  felt  band,  which  is  in  shape  like 
the  wire  sieve.     It  passes  between  smooth  metal  rollers, 


PAPER,  PAINTS   AND    OTIIER   COLOURS.  67 

which  squeezes  more  water  out,  aud  at  last  over  several 
smooth,  large,  hollow,  metal  rollers,  which  are  made  hot 
hy  passing  steam  through  them  inside.  From  the  drying 
rollers  it  may  he  at  once  wound  upon  the  reel,  and  sized 
afterwards,  or  it  may  he  passed  through  the  size,  and 
again  dried  and  pressed  between  rollers.  For  the 
commoner  kinds  of  paper,  such  as  wall-paper  and  brown 
packing-paper,  a  so-called  size  is  made  by  dissolving 
together  resin  (see  §  67),  soda  (see  §  120),  and  a  little 
alum.     Sometimes  the  size  is  mixed  with  the  pulp. 

§  58.  Straw,  Esparto,  and  Wood  Paper. — Esparto 
is  a  kind  of  sedge  growing  in  South  Spain  and  North 
Africa.  The  plant  is  pulled,  and  dried  in  the  sun.  The 
wood,  when  used  for  paper-making,  is  sometimes  torn 
into  shreds  by  rough  grindstones.  The  paper  made  from 
these  substances  is  brittle,  hut  their  pulp,  when  mixed 
with  linen  or  cotton-pulp,  gives  stiffness  to  the  paper,  and 
this,  together  with  its  cheapness,  is  why  it  is  used  for 
wall-papers. 

Questions. — What  is  paper  made  from  ?  How  are  rags  cleaned 
for  making  paper  ?  How  are  rags  made  into  a  pulp  ?  How  can  a 
sheet  of  moist  pulp  be  got  ?  How  is  the  pulp  dried  ?  What  is 
done  to  blotting-paper  to  stop  ink  from  spreading  ?  How  is  the 
paper  smoothed  ?     How  are  wall-papers  sized. 


XXIII. 

Paints,  Linseed  Oil,  White  Lead,  Zinc-white. 

Things  to  be  Seen. — Linseed — linseed  meal — linseed  oil 
— oil  of  turpentine — litharge — sugar  of  lead — ivhite 
lead — vinegar— tan — zinc — oxide  of  zinc — arsenide  of 
copper — oxide  of  chromium — iron-rust — some  oil-cloth. 

§  59.  Paints  and  other  Colours. — The  plaster, 
mortar,  wood,  or  iron  .on  the  outside  of  houses,  and  the 
wood  inside  the  houses,  is  often  painted,  so  that  the 
weather  cannot  act  upon  it  outside,  and  so  that  it  can, 
when  inside,  he  made  to  look  like  stone  or  a  different 


68  PAINTS   AND   OTHER   COLOURS. 

kind  of  wood,  and  be  easily  cleaned.  Paint  for  such  pur- 
poses is  generally  made  of  Linseed  Oil,  oil  of  turpentine 
(see  §  67),  and  some  white  or  coloured  powder,  according 
to  the  colour  of  the  paint  which  is  wanted.  The  seed  of 
the  flax  of  which  linen  is  made  (see  §  55)  is  linseed; 
these  seeds,  when  ripe,  are  very  slippery,  and  could  not 
easily  he  ground.  They  are  therefore  first  bruised ;  and 
this  is  done  by  letting  them  fall  between  two  strong 
metal  rollers,  which  have  ridges  on  them,  and  which  are 
very  close  together,  and  turn  round.  The  bruised  seed  is 
then  spread  upon  the  bottom  of  a  ring-shaped  trough 
having  a  hard  bottom,  and  a  heavy  granite  roller  is  made 
to  roll  round  the  trough.  This  crushes  the  seed  into  a 
sort  of  flour  or  meal,  called  linseed  meal,  which  is  some- 
times used  for  poultices.  The  linseed  meal  is  then  put  into 
strong  bags,  warmed,  and  then  pressed  very  much,  so  that 
the  oil  is  squeezed  out.  If  the  meal  be  heated  before  being 
pressed,  more  oil  is  got,  but  it  is  not  quite  so  good.  The 
mass  from  which  the  oil  has  been  squeezed  is  called  oil- 
cake, and  is  very  useful  for  fattening  cattle.  This  linseed 
oil  cannot  be  used  at  once  for  making  paint,  because  it 
does  not  dry;  but  if  it  be  boiled  for  a  short  time,  or 
allowed  to  stand,  with  frequent  shakings,  for  a  longer 
time,  with  a  little  lead-rust  (oxide  of  lead,  litharge)  and 
sugar  of  lead  (acetate  of  lead,  got  by  dissolving  litharge 
in  vinegar),  it  gets  the  power  of  drying  in  a  few  hours. 

White  paint  is  generally  made  by  mixing  linseed  oil 
with  White  Lead  and  oil  of  turpentine  (see  §  67) ;  and 
white  lead  is  made  as  follows : — The  metal  lead  is  cast 
into  forms  like  a  gridiron.  The  lead  is  put  on  the  top  of 
earthen  pots  in  which  there  is  some  vinegar.  The  pots 
and  lead  are  covered  loosely  with  boards,  and  on  the  top 
of  these  is  put  some  old  tan  which  has  been  used  for 
tanning  leather  (see  §  97).  Another  set  of  vinegar-pots 
stands  on  these,  then  more  lead,  planks,  and  tan,  and  so 
on,  until  a  high  pile  is  made.  In  two  or  three  months 
the  pile  is  unbuilt,  and  the  lead  is  found  to  be  almost  all 


PAINTS    AND    OTIIER    COLOURS,  OIL-CLOTII.  G9 

changed  into  a  white  hrittle  substance,  called  white  lead. 
This  white  lead  is  found  to  be  made  of  lead  and  oxygen 
and  water  and  carbonic  acid.  The  oxygen  and  the  water 
it  has  got  from  the  moist  air.  The  carbonic  acid  has  been 
got  from  the  fermenting  tan  (see  §§  106,  115).  The 
vinegar  vapour  has  helped  the  lead-  to  rust  or  oxidise,  I 
do  not  know  how. 

The  white  lead  is  broken  and  scraped  away  from  any 
unchanged  lead,  and  ground  with  water  to  a  kind  of  milk. 
On  standing,  the  coarser  grains  settle  first ;  those  which 
settle  last  are  the  smallest  (compare  §  26)  ;  the  coarser  are 
ground  again.  The  white  mud  is  scooped  out,  drained, 
and  dried.  This,  when  ground  with  boiled  linseed  oil 
and  mixed  with  oil  of  turpentine  (see  §  67),  is  white 
paint. 

§  60.  Zinc-white  is  often  used  instead  of  white  lead. 
It  is  the  rust  or  oxide  of  zinc,  and  is  therefore  to  be  got 
by  burning  zinc.  Zinc,  on  being  heated,  melts,  and  then, 
on  being  heated  very  hot  indeed,  boils  just  as  melted  ice, 
that  is,  water,  does.  When  the  vapour  of  zinc  meets  with 
the  air  at  this  very  great  hotness  it  quickly  oxidises  or 
burns,  and  its  oxide  is  a  white  powder,  called  zinc- 
white. 

Most  coloured  paints  used  for  house-painting  are  lead — 
or  zinc — paint  mixed  with  coloured  powder.  Green  paints 
are  generally  so  coloured  hj  mixing  with  the  white  paint 
bodies  containing  copper,  arsenic,  or  chromium.  Iron- 
rusts  (that  is,  oxides)  of  different  kinds  and  in  different 
quantities  give  yellows,  browns,  and  blacks.  Black  paints 
are  also  made  by  using  the  powder  of  some  kinds  of  coal 
which  contain  silica.  The  colours  of  most  woods  and 
stones  are  like  one  or  other  of  these  in  colour.  As  oil  of 
turpentine  smells  badly,  impure  spirits  of  wine,  called 
methylated  spirit,  is  sometimes  used  instead  of  it  to  mix 
with  the  linseed  oil  and  white  lead. 

§  61.  Oil-cloth. — Oil-cloth  is  canvas  or  hempen  cloth, 
one  side  of  which  has  been  painted  in  oil  colours. 


70  COLOURS    OP   WALL-PAPERS. 

Questions. — Why  and  on  what  is  paint  used  ?  What  is  paint 
made  of?  What  is  linseed  oil?  How  is  it  got?  What  is  oil- 
cake ?  How  is  linseed  oil  made  to  dry  ?  How  is  white  lead  made, 
and  what  is  it  made  of  ?  How  is  white  paint  made  ?  How  are 
green  paints  made  ?  How  are  yellow,  brown,  and  black  paints 
made  ?  What  can  be  used  instead  of  turpentine  in  making  paints  ? 
What  is  oil-cloth  ? 


XXIV. 


Colours  of  Wall-papers,  Cane,  Rushes,  Wicker, 
Horse-hair. 

Things  to  be  Seen. — Pipe-clay — size — whiting — Prussian 
blue  —  verditei ultramarine  (artificial)  —  chrome- 
yellow —  Brazil  wood — arsenite  of  copper — umber — 
cane — rushes — willow  and  wicker — horses'  hair  and 
toebs  of  horse-hair. 

§  62.  Colours  of  Wall-papers.— The  paper  having 
been  made  in  long  rolls  (according  to  §  57),  and  very 
well  sized,  is  laid  upon  a  table  and  brushed  over 
with  a  mixture  of  white  clay  (china-clay,  pipe-clay)  and 
size.  Generally,  wall-papers  are  first  coloured  all  over, 
or  tinted,  before  the  pattern  is  given  to  them.  The 
colours  wanted  are  in  such  cases  mixed  with  the  white 
clay  and  size.  The  colours  used  to  this  end  are  usually 
what  are  called  "  lake  "  colours — that  is,  the  colouring- 
matter  is  in  union  with  the  earth  alumina.  Alumina  is 
the  oxide  of  the  metal  aluminum.  After  hanging  up  to 
dry,  the  paper  is  laid  upon  a  hard  smooth  table  with  the 
clayed  face  down,  and  the  upper  face  is  rubbed  with  a 
smooth  brass  brighten er.  The  coloured  patterns  are 
stamped  upon  the  paper  \>y  a  wooden  block  of  the  shape 
of  the  pattern,  and  which  has  been  dipped  in  the 
coloured  licprid.  If  a  pattern  has  twelve  colours, 
twelve  blocks  of  the  shape  of  the  outline  of  the 
pattern  are  used ;  but  the  wood  of  each  block  is  so  cut 
away  that  only  that  part  is  left  to  touch  the  paper 
where  a  certain  colour  is  required.     By  this  means  only 


COLOURS  OF  WALL-PAPERS,  CANE,  RUSHES,  WICKER.       71 

one  colour  is  used  on  each  block.  The  colours  used  in 
paper-staining  are  very  numerous.  White  is  usually 
whiting  (see  §  26).  Blue  is  Prussian  blue,  that  is,  a  body 
made  of  iron,  carbon,  nitrogen  (see  §  1^6);  or  else 
Veediter,  which  is  a  mixture  of  oxide  of  copper  and  lime, 
or  else  Ultramarine,  a  mixture  of  a  great  many  things, 
and  which  is  made  so  as  to  be,  in  colour  and  in  the  things 
of  which  it  is  made,  like  a  natural  mineral  of  the  same 
name,  which  is  rare  and  dear.  Yellow  colours  are  often 
got  by  boiling  the  berries  of  the  "  dyer's  weed  "  or  "  weld." 
Chrome-yellow  is  a  substance  made  of  oxygen  and  the 
two  metals  chromium  and  lead.  Beds  are  got  by  boiling 
Brazil  wood  with  water;  the  tree  grows  in  Brazil,  in  the 
West  Indies,  and  in  Japan.  Greens  usually  contain 
copper,  or  copper  and  arsenic.  A  mixture  of  Prussian- 
blue  and  chrome-yellow  also  gives  a  green.  Brown  colours 
are  the  natural  mixtures  of  oxide  of  iron  and  manganese 
with  clay,  and  are  called  umber.  Most  other  shades 
are  got  by  mixing  two  or  more  of  the  above  colours 
in  different  proportions.  Wall-papers  coloured  with 
arsenic  are  poisonous. 

As  most  furniture  is  made  of  wood,  and  as  the  different 
kinds  of  wood  have  been  already  described  (see  §  34), 
there  is  not  much  left  to  be  said  about  such  furniture  as 
is  made  of  wood. 

§  63.  Cane. — The  seats  of  chairs  are  often  made  of 
cane.  This  cane,  which  is  really  the  stem  of  a  kind  of 
palm,  grows  in  Borneo  and  the  neighbouring  islands.  It 
is  simply  split,  and  then,  being  woven  across  the  frame  of 
the  chair,  forms  the  seat. 

§  64.  Rushes. — The  common  rush  (not  the  bulrush), 
which  grows  in  marshy  places,  is  sometimes  used  for 
chair-bottoms.  Such  chair-bottoms  are  soft,  but  difficult 
to  clean. 

§  65.  Wicker. — Chairs  are  often  made  entirely  of 
wicker ;  and  it  is  of  this  that  common  baskets,  such  as 
clothes-baskets,  are  made.     Wicker  is  the  small  branch  of 


72  WICKER,  HORSE-HAIR,  VARNISH. 

the  willow-tree,  or  the  sprout  of  the  young  willow-plant  J 
the  latter  is  usually  called  osier.  Osier-beds  are  nurseries 
of  young  willows.  After  these  are  cut,  they  are  stacked 
for  a  time,  and  then  drawn  from  end  to  end  between  two 
knife-blades  fastened  in  the  ground,  which  cross  one 
another  like  the  blades  of  a  partly-opened  pair  of  scissors. 
The  bark  of  the  willow  is  thus  stripped  off,  and  the 
wicker  is  ready  to  be  worked  iDto  baskets.  Sometimes 
the  bark  is  left  on  ;  it  is  so  left  in  fish-baskets. 

§  66.  Horse-hair. — Horse-hair  web  is  simply  the  web 
made  from  the  hair  of  horses'  manes  and  tails.  It  is  used 
for  covering  sofas  and  chair-bottoms,  being  then  stretched 
over  some  stuffing.  Very  often  so-called  horse-hair  webs 
are  only  half  horse-hair,  that  is,  the  warp  is  horse-hair,  but 
the  woof  is  cotton  or  worsted.  Horse-hair  is  also  used  for 
stuffing  mattresses,  and  for  sieves  (see  §  95). 

Questions. — What  is  first  clone  to  paper  in  order  to  make  wall- 
paper of  it  ?  What  are  "lake"  colours?  How  are  the  colours 
given  to  the  paper  ?  What  is  the  white  of  wall-papers  made  of  ? 
What  is  the  blue  made  of?  What  is  "  venliter  "  ?  What  is 
"  ultramarine  "  ?  What  are  yellows  made  of  ?  What  are  reds  made 
from  ?  What  are  greens  made  of  ?  What  are  browns  made  of  ? 
What  is  cane  ?  What  is  rush  ?  What  is  wicker  ?  What  is  osier  ? 
How  is  osier  made  ready  for  use  as  wicker  ?  How  is  horse-hair  web 
made,  and  what  is  it  used  for  ? 


XXV. 

Varnish,  Turpentine,  Magnesia,  Resin,  Shell-lac, 
Spirits  of  Wine,  Lacquer. 

Things  to  be  Seen. —  Varnish — linseed  oil — gum  copal 
— oil  of  turpentine — magnesia — raw  turpentine — rosin 
— size — shell-lac — spirits  of  wine. 
§  67.  Varnish. — The  varnish  generally  used  for  wood 
in  houses  is  a  mixture  of  drying  linseed  oil  (see  §  59),  gum 
copal,  and  oil  of  turpentine  (called  also  spirits  of  turpen- 
tine, or  simply  turpentine — see  §  36).     Tne  linseed  oil  is 
made  into  drying  linseed  oil  by  boiling  it  with  a  little 


VARNISH,  FRENCn    POLISH".  73 

Magnesia.  Magnesia  is  the  rust  or  oxide  of  the  metal 
magnesium,  and  is  got  by  heating  the  natural  carbonate 
of  magnesia,  just  as  quick-lime  is  got  by  heating  limestone 
(see  §  3).  After  settling,  the  oil  is  ready  for  making 
varnish.  Gum  oopal  is  a  kind  of  resin,  which  is  produced 
by  some  trees  growing  both  in  the  East  and  West 
Indies.  Turpentine  is  formed  in  European  trees  of  the 
nature  of  pine-trees  and  fir-trees.  Holes  are  cut  into  the 
wood  of  such  trees  a  little  above  the  ground,  and  the 
turpentine  collects  in  the  holes.  When  fresh,  it  is  a  thick 
colourless  liquid,  "which  hardens  after  a  time  in  the  air, 
and  then  is  like  old  honey.  If  turpentine  be  boiled  with 
water  in  a  still,  water  and  an  oil  come  over  together,  the 
oil  floating  on  the  water.  The  oil  is  called  Oil  of  Tur- 
pentine, or  spirit,  of  turpentine,  or  turpentine,  or  turps. 
The  substance  which  remains  in  the  still  is  called  Eesin, 
or  Eosin.  Varnish  is  made  out  of  linseed  oil,  copal,  and 
oil  of  turpentine,  as  follows : — The  copal  is  melted  over 
a  fire  in  a  copper  pan,  but  not  over-heated.  Hot  linseed 
oil  is  stirred  in,  and  mixes  with  the  copal ;  the  two  are 
gently  boiled  together,  and  the  oil  of  turpentine  is  added 
in  small  quantities  at  a  time,  and  stirred  in. 

If  varnish  be  applied  directly  to  wood,  a  great  deal  of 
it  sinks  into  the  wood  and  is  lost.  To  prevent  this,  the 
wood  is  first  brushed  over  with  size  (that  is,  thin  glue, 
see  §  25).  This  stops  up  the  pores  of  the  wood,  and  is 
not  washed  away  by  the  varnish. 

§  68.  French  Polish. — This  is  used  for  the  finer 
kinds  of  woodwork.  It  is  made  by  dissolving  Shell-lao 
in  spirits  of  wine.  Shell-lac  is  got  as  follows : — In  the 
East  Indies,  in  Assam,  and  Siam,  there  are  certain  trees 
which  are  kinds  of  fig-trees.  The  twigs  of  these  trees  are 
sometimes  pricked  by  little  insects,  and  the  juice  which 
comes  out  hardens  and  coats  the  twig.  When  this  hard 
stuff,  which  is  a  resin,  is  melted,  and  squeezed  through  a 
cloth  to  cleanse  it,  and  allowed  to  fall  on  a  cool  substance 
to  harden  it,  it  is  called  shell-lac.     If  wine  or  beer  (see 


74  FRENCH   POLISH,  LACQUER. 

§  115),  or  other  liquid  which  has  heen  fermented  (see 
§  115),  is  heated  till  it  boils,  and  if  the  part  which  boils 
away  first  as  a  gas  is  cooled,  and  so  collected,  it  is  found 
to  contain  a  liquid  called  Spirit  of  Wine,  which  contains 
carbon,  oxygen,  and  hydrogen.  To  make  French  polish, 
the  shell-lac  is  simply  allowed  to  stand  in  the  spirit  of 
wine,  and  occasionally  shaken,  till  it  is  nearly  all  dis- 
solved ;  it  is  then  strained,  and  is  fit  for  use.  The  pores 
of  the  wood  are  often  first  filled  with  a  mixture  of  plaster 
of  Paris  and  tallow.  The  polish  is  rubbed  on  with  little 
tufts  of  cotton-wool  until  the  spirit  has  passed  off,  so  that 
nothing  remains  but  a  thin  sheet  of  shell-lac.  Some- 
times gum  copal,  or  other  resins,  such  as  Sandarach,  a 
gum  from  a  kind  of  juniper  growing  in  JSTorth  Africa,  are 
added  to  the  shell-lac. 

§  69.  Lacquer  is  a  kind  of  French  polish  used  for 
metals  to  protect  them  from  the  air.  It  is  made  of  spirit 
of  wine  and  the  lightest-coloured  shell-lac,  to  which  is 
added  more  or  less  of  the  resin  called  Dragon's-Bloop, 
produced  by  certain  trees  and  plants  in  the  Fast  Indies, 
one  of  which  is  the  rattan-cane,  of  which  seats  of  chairs 
are  often  made.  Metal  objects  to  be  lacquered  should 
first  be  heated,  and  the  lacquer  brushed  on  them  while 
they  are  hot.  If  this  be  not  done,  the  surface  of  the 
lacquer  becomes  dull  and  grey.  Brass  door-handles, 
curtain-rings,  brass  brackets,  and  hinges  are  generally 
lacquered. 

Questions. — What  is  common  varnish  made  of?  What  is  mag- 
nesia ?  How  is  it  made  ?  What  is  gum  copal  ?  Where  is  turpen- 
tine found  ?  How  is  oil  or  spirit  of  turpentine  made  from  it  ? 
How  is  resin  got  ?  What  is  done  to  the  wood  to  prevent  the 
varnish  sinking  into  it?  What  is  French  polish  made  of?  How 
is  shell-lac  formed  ?  How  is  it  cleaned  ?  •  What  is  spirit  of  wine 
made  from?  How  is  it  made?  What  elements  is  it  made  of? 
How  is  the  wood*  often  made  ready  to  take  the  French  polish  ? 
How  is  the  French  polish  used  ?  What  is  lacquer  ?  How  is  it 
used  ?    On  what  things  is  it  used  ? 


WOOLLEN,  WORSTED,  CARPETS.  75 


XXVI. 

Woollen,  Worsted,  Carpets,  Cocoa-nut  Fibre, 
Looking-glasses. 

Things  to  be  Seen. — Sheep's  wool — woollen  yarn — worded 
thread — pieces  of  carpet  of  several  kinds — cocoa-nut 
fibre — either  a  cocoa-nut  with  its  fibre  or  a  drawing 
of  one — a  sheet  of  tin-foil — a  small  jriece  of  plate- a  lass 
— a  little  mercury. 
§  70.  Woollen,  Worsted. — The  sheep  is  shorn  about 
once  a-year,  and  the  fleece  is  soon  after  washed  in  water. 
This  washes  out  a  soapy  substance  which  exists  in  large 
quantities  in  the  wool.  It  is  again  washed  in  soap  and 
water  to  clean  it  from  grease  and  dirt.  After  drying, 
it  is  combed  between  steel  combs,  which  are  generally  set 
on  wheels  and  driven  by  machinery.  This  straightens 
the  fibres,  and  separates  the  longer  from  the  shorter ;  the 
former  are  used  for  worsted,  and  the  latter  for  broadcloth. 
The  working  of  the  wool  into  threads  or  woollen  yarn,  and 
its  weaving,  is  very  much  like  the  working  of  cotton- 
wool into  thread  and  calico  (see  §  54).  Before  combing, 
however,  the  wool  is  rubbed  with  oil,  and  the  combs  used 
are  hot.  This  makes  the  fibres  slide  better,  and  so  lie 
smoothly  side  by  side.  As  the  combed  wool  leaves 
the  combing-wheels  it  is  slightly  twisted,  and  then 
stretched,  and  finally  twisted  and  spun  on  spindles, 
which  can  be  taken  out,  leaving  the  worsted  as  a 
"hank."  The  weaving  of  wool  need  not  be  described, 
it  is  so  like  the  weaving  of  calico.  Blankets  are  woven 
loosely. 

§  71.  Carpets  are  usually  made  half  of  hempen  or 
linen  threads  and  half  of  worsted.  Sometimes  the  warp 
is  of  hemp  or  jute  and  the  woof  of  wool,  sometimes  the 
reverse.  The  hemp  threads  are  hard  and  narrow,  the 
worsted  is  soft  and  thick,  so  that  when  woven  together 
the  worsted  hides  the  hemp.     If  the  projecting  loops  of 


76  COCOA-NUT    FIBRE,  LOOKING-GLASSES. 

the  worsted  be  cut  through,  the  ends  stick  up,  and  so  give 
a  "  pile  "  to  the  carpet. 

§  72.  Cocoa-nut  fibre. — The  cocoa-nut  is  the  fruit  of 
the  cocoa-palm,  a  tree  which  grows  in  most  very  hot 
countries  near  the  sea,  and  which  is  often  fifty  or  a 
hundred  feet  high.  It  has  a  straight  stem  without 
branches,  and  leaves  only  at  the  top.  Close  beneath  the 
large  leaves,  and  thus  sheltered,  hang  the  cocoa-nuts. 
These  are  made  up  (looking  at  them  from  the  outside)  of 
a  thick  husk  of  fibre  matted  together,  then  the  nut  as  we 
generally  get  it — that  is,  a  very  hard  shell — holding  the 
white  stuff,  which  is  eaten,  and  from  which  cocoa-nut  oil 
is  pressed,  and,  lastly,  the  water,  or  milk.  The  husk  is 
cut  from  end  to  end  on  one  side,  so  as  to  do  as  little 
injury  as  possible  to  the  fibres,  which  run  mainly  in  the 
same  direction.  The  libres  are  separated,  straightened, 
and  twisted  into  strings,  cords,  and  cables.  The  cords 
are  woven  into  door-mats  and  matting,  which  is  very 
tough,  and  stands  a  great  deal  of  wear,  and  is  not  hurt  by 
wet. 

§  73.  Looking-glasses. — Flat  mirrors,  called  looking- 
glasses,  are  made  by  covering  one  side  of  a  sheet  of  plate- 
glass  (see  §  27)  with  the  metal  tin  (see  §  21).  This  is 
done  as  follows  : — A  very  smooth  and  even  table  of 
polished  marble  is  so  supported  that  it  can  be  tilted. 
Around  its  edges  are  rims,  and  close  to  the  rims  are 
grooves.  A  thin  sheet  of  tin,  called,  when  so  thin, 
tin-foil,  is  laid  upon  the  table,  and  brushed  flat  with 
a  soft  brush.  A  little  mercury  is  poured  upon  this,  and 
gently  rubbed  all  over  it  with  a  woollen  pad.  The 
mercury  sinks  into  and  mixes  with  the  upper  face  of 
the  tin,  just  as  water  would  sink  into  and  mix  with  a 
face  of  glue.  Next,  some  more  mercury  is  poured  on,  till 
the  metal  is  about  a  tenth  of  an  inch  thick.  The 
surface  is  wiped  clean.  A  clean  sheet  of  paper  is  laid 
upon  the  mercury,  wholly  covering  it,  excepting  a  little 
space  at  one  edge.     The  sheet  of  plate-glass  is  very  care- 


LOOKING-GLASSES.  77 

fully  cleaned  and  warmed,  and  laid  upon  tho  table,  so 
that  one  of  its  edges  rests  upon  the  edge  of  paper  at  the 
end  where  the  mercury  is  hare.  The  paper  is  drawn,  and 
the  glass  pushed  to  follow  it.  Tho  paper  wipes  oil'  all 
dirt  from  the  mercury  surface  and  shields  it  from  any 
falling  dust.  Dust  is  almost  always  Hying  about.  When 
all  tho  glass  is  quite  above  the  metal,  weights  are  put 
upon  the  glass,  and  the  table  is  tilted.  This  squeezes  out 
most  of  the  mercury.  Then,  after  a  time,  the  edges  are 
trimmed  with  a  knife — that  is,  the  metal  is  cut  round  close 
to  the  glass — and  the  whole  let  stand  on  the  slant  for  a  long 
time,  the  slant  being  made  time  after  time  greater  and 
greater,  till  at  last  the  glass  stands  on  its  edge.  A  great 
deal  of  the  mercury  gradually  drains  from  the  tin ;  and  a 
great  deal  of  that  which  does  not  drain  olf  passes  as  a  gas 
into  the  air.  The  backs  of  the  mirrors  are  covered  to 
protect  the  tin-mercury  from  rough  usage.  When  you  see 
yourself  or  anything  else  in  a  mirror,  what  happens  is  this 
— The  light  which  comes  from  the  thing  strikes  the  face  of 
the  glass  ;  most  of  it  goes  through  the  glass,  and  meets  the 
back  of  the  glass  and  the  smooth  metal  at  the  same  time, 
because  they  are  touching — that  is,  in  the  same  place. 
The  light  is  turned  back  from  the  metal  surface,  passes 
through  the  glass  again,  comes  out  at  the  front,  and, 
passing  through  the  air,  reaches  your  eye. 

Questions. — What  is  wool  ?  How  is  the  fleece  cleaned  ?  What 
is  then  done  to  the  wool  so  as  to  bring  it  into  the  state  called 
"  hank  "  ?  What  is  woven  along  with  worsted  in  making  carpets  ? 
How  is  the  "pile"  of  carpets  made?  What  is  cocoa-nut  fibre  ? 
What  is  the  whole  cocoa-nut  like  ?  What  is  cocoa-nut  fibre  used 
for  ?  Why  should  it  be  so  used  ?  How  are  flat  looking-glasses 
made  ?  (divide  this  question).  What  is  the  course  of  light  from  a 
thing  which  you  see  iu  a  mirror  to  your  eyes  ? 


78  GERMAN    SILVER,  BRITANNIA   METAL. 


XXVII. 

German  Silver,  Britannia  Metal,  Silver. 

Things  to  be   Seen. — Some   nickel  ore — nickel — zinc — 

copper  —  Britannia   metal  —  antimony  — sulphide  &f 

antimony — charcoal — carbonate  of  soda — ore  of  silver 

— silver — litharge — lime — sulphur — bone  ashes — green 

vitriol — mercury. 

§74.  German  Silver. — German  silver  is  a  mixture 

(or   alloy)    of  three   metals — Nickel,  zinc,  and  copper. 

These  are  melted  together  in  different  proportions,  according 

to  the  use  to  which  the  alloy  is  to  be  put.    For  forks,  spoons, 

tea-pots,  and  such  things,  the  proportion  is  about  one  of 

nickel,  one  of  zinc,  and  two  of  copper.     Nickel  is  found 

in  nature  as  an  ore,  which  contains  arsenic  and  sulphur 

along  with  the  nickel.     Most  of  the  arsenic  can  be  and  is 

driven  off  by  heat  alone,  and  the  rest  is  driven  off  when 

charcoal  is  heated  with  the  ore.     The  ore  so  freed  from 

arsenic  is  next  heated  with  sulphur  and  potash,  whereupon 

the  nickel  and  sulphur  unite,  and  can  be  separated  as  a 

solid  from  the  impurities  which  the  potash   has    made 

soluble.      The  sulphide  of   nickel  becomes  an  oxide  by 

roasting,  and  the  oxide  gives  metallic  nickel  when  heated 

with  charcoal,  because  the  charcoal  joins  with  the  oxygen 

and  goes  away  as  a  gas.     German  silver  is  used  for  forks 

and  spoons. 

§  75.  Britannia  Metal. — Britannia  metal  is  a  mixture 
or  alloy  of  tin  and  a  little  Antimony,  and  sometimes  a 
little  copper.  Antimony  is  sometimes  found  as  a  metal, 
but  more  frequently  united  with  sulphur  and  other 
bodies.  The  sulphide  of  antimony  melts  very  easily;  so 
on  simply  heating  the  ore,  the  sulphide  melts  first,  and 
collects  at  the  bottom  of  the  melting-pot  or  furnace.  The 
sulphide,  on  being  heated  with  charcoal  and  carbonate  of 
soda  (to  which  oxide  of  iron  is  sometimes  added),  gives 
up  its  sulphur,  and  becomes  metallic.     Another  way  is  to 


SILVER.  t  \) 

thrust  metallic  iron  into  the  melted  sulphide  of  antimony, 
whereupon  the  iron  and  sulphur  unite,  leaving  the 
antimony  as  a  melted  metal.  Britannia  metal  is  used  for 
making  tea-pots. 

§  76.  Silver. — Silver  is  sometimes  found  as  a  metal, 
hut  chiefly  as  an  ore,  containing  sulphur,  lead,  antimony, 
or  arsenic,  and  mixed  with  rocks.  The  ore  is  broken  into 
small  pieces  and  sorted.  Those  pieces  which  are  richest 
in  silver  are  crushed  small,  and  mixed  with  the  oxide  of 
lead,  oxide  of  iron,  lime,  and  charcoal.  The  lead  and  the 
silver  both  lose  their  sulphur,  and  mix  as  melted  metals. 
The  alloy  of  silver  and  lead  is  then  put  into  a  furnace 
and  melted,  and  air  blown  upon  the  melted  mass,  where- 
upon the  lead  only  is  oxidised,  and  the  melted  oxide  of 
lead  is  blown  off.  At  last  the  nearly  pure  silver  is  put  in 
a  cup  made  of  bone  ashes,  and  again  melted  and  blown 
on.  The  oxide  of  lead  now  formed  sinks  into  the  bone 
ash  and  leaves  the  silver  pure.  To  get  more  silver,  the 
pieces  of  the  original  ore  which  were  poorest  in  silver  are 
very  finely  crushed  with  water.  The  whole  is  allowed  to 
partly  dry  to  a  mud.  This  is  mixed  with  salt  and  "  green 
vitriol"  (sulphate  of  iron),  and  mercury  is  added.  The 
whole  is  worked  together.  The  silver  leaves  everything 
and  unites  with  the  mercury.  This  alloy  of  mercury  and 
silver,  called  an  amalgam  of  silver,  is  washed  free  from 
the  rocky  mini  above  it.  It  is  then  put  into  canvas  bags 
and  pressed.  Mercury  containing  some  silver  runs 
through,  and  is  kept  for  future  use.  Silver  containing 
some  mercury  remains  in  the  bags.  This  is  heated  in 
such  a  way  as  to  drive  off  the  mercury  which  is  collected, 
and  leave  the  silver  behind,  and  this  is  freed  from  any 
lead  in  it,  as  described  before.  In  some  places  where 
ores  of  lead  are  worked,  the  lead  contains  a  very  small 
quantity  of  silver.  To  get  at  this  without  rusting,  that 
is,  oxidising  all  the  lead,  the  whole  is  melted,  and 
allowed  to  cool  very  gradually.  The  pure  lead  solidifies 
first,  and  can  be  ladled  out  by  a  ladle  having  small  holes 


80  PLATE,  SILVER-PLATE. 

in  it.  The  metal  -which  is  left  gets,  of  course,  richer  and 
richer  in  silver.  At  last  it  is  so  rich  that  it  pays  to 
oxidise  the  rest  of  the  lead,  as  above  described,  and  leave 
the  silver. 

Questions. — What  is  German  silver  made  of?  What  is  it  used 
for  ?  In  what  state  is  nickel  found  in  nature  ?  How  is  nickel  ore 
freed  from  arsenic  ?  How  is  the  nickel  then  got  as  a  metal  ? 
What  is  Britannia  metal  made  of?  In  what  state  is  antimony 
found  in  nature  ?  What  is  the  common  ore  of  antimony  made  of? 
In  what  way  is  antimony  got  from  its  ore  ?  In  what  state  is  silver 
usually  found  ?  How  are  the  silver  and  lead  of  the  ore  got  together 
free  from  other  things  ?  How  is  the  lead  got  rid  of  ?  How  are 
poor  ores  treated  ?  How  is  the  mercury  got  rid  of  from  the  silver  ? 
How  is  silver  got  from  lead  when  there  is  very  little  silver  in  the 
alloy  ? 


XXVIII. 

Plate,  Silver-plate,  Silvering,  Electroplating. 
Things  to  be  Seen. — A  clean  sheet  of  copper — a  thin  sheet 
of  silver — a  little  mercury — nitric  acid — a  drawing 
showing  electro-plating. 

§77.  Plate,  Silver-plate.  —  Silver  does  not  easily 
tarnish  or  rust.  It  blackens  in  the  air,  if  there  is  sulphur 
in  the  air,  as  is  generally  the  case  in  rooms  where  gas  is 
burnt,  or  into  which  the  gas  from  burning  coal  enters. 
And  this  is  generally  the  case  in  towns ;  for,  though  the 
gases  from  our  own  fires  may  all  go  up  the  chimney,  the 
gases  from  other  people's  chimneys  come  in  at  our  doors 
and  windows.  However,  because  this  sulphur-tarnishing 
does  not  corrode  the  silver  deeply,  because  it  is  easily 
rubbed  off,  because  the  clean  silver  is  so  pretty,  and 
because  it  has  no  taste  or  smell,  like  iron,  copper,  and  tin, 
silver  spoons  and  forks,  tea-pots,  and  so  on,  are  pleasant 
to  use,  but  they  are  dear.  If  we  coat  or  cover  a  thing 
made  of  a  cheap  metal  with  silver,  we  have  the  main 
advantages  of  the  silver,  together  with  cheapness.  To  do 
this  there  are  various  plans.  Upon  a  square  bar  of  copper 
having  a  clean  upper  surface,  a  clean  sheet  of  silver  is 


SILVERING,  ELECTRO-PLATING   WITH    SILVER.  81 

laid ;  the  two  are  bound  together  with  iron  wire,  and  into  the 
crack  between  them  a  little  borax  (see  §  83)  is  stalled  in  all 
round.  This  body  easily  melts;  it  shuts  out  the  air,  and 
so  prevents  the  copper  from  rusting;  it,  moreover,  dis- 
solves any  copper  rust  which  may  be  formed.  The  two 
(copper  and  silver)  are  put  together  in  a  furnace,  and  by- 
and-by  they  stick  together  and  form  one  piece  of  metal, 
in  doing  which  they  squeeze  out  the  melted  borax  and 
the  rust  which  it  has  dissolved.  The  copper  bar  thus 
faced  with  silver  can  now  be  rolled,  as  thin  as  you  please, 
between  rollers,  and  worked  and  hammered  into  any 
shape  wanted. 

§  78.  Silvering. — Thin  coats  of  silver  are  given  to 
small  pieces  of  metal  by  shaking  or  smearing  the  articles 
with  amalgam  of  silver  (a  mixture  of  silver  and  mercury), 
to  which  a  little  dilute  aquafortis  (see  §  127)  has  been 
added.  The  amalgam  sticks  to  the  metal,  and  the  mer- 
cury being  afterwards  driven  off  by  heat,  the  silver  alone 
is  left. 

§  79.  Electro-plating  with  Silver.  —  We  cannot 
understand  the  process  at  present,  but  the  plan  is  this  : — 
Some  liquid  containing  dissolved  silver  is  taken ;  in  this 
are  hung,  side  by  side,  a  piece  of  silver  and  the  object 
which  has  to  be  electro-plated — that  is,  covered  with 
silver.  In  another  vessel  is  put  some  dilute  sulphuric 
acid  (see  §  127),  and  side  by  side  in  this  vessel  are  placed, 
but  not  touching  one  another,  a  piece  of  zinc  and  a  piece 
of  copper.  One  end  of  a  metal  wire  is  fastened  to  the 
copper  in  the  second  vessel  and  the  other  end  to  the  silver 
in  the  first.  One  end  of  a  second  wire  is  fastened  to  the 
zinc  in  the  second  vessel  and  the  other  to  the  article  to 
be  plated  in  the  first.  Then,  on  standing  for  some  time, 
it  is  found  that  the  piece  of  silver  in  the  first  vessel  is 
eaten  away ;  so  is  the  zinc  in  the  second  vessel ;  but  the 
article  in  the  first  vessel  is  coated  with  silver.  This  is 
called  electro-plating,  because  while  it  is  going  on,  elec- 
tricity is  passing  round  and  round  from  the  zinc  in  the 

F 


82  ELECTRO-PLATING    WITH    SILVER,  STEEL. 

second  vessel  through  the  sulphuric  acid  in  that  vessel  to 
the  copper,  up  the  copper,  along  the  wire  to  the  silver  in 
the  first  vessel,  down  the  silver  through  the  silver  solu- 
tion to  the  article  being  plated,  up  this,  along  the  wire  to 
the  zinc,  and  down  the  zinc,  to  where  it  started. 

Questions. — What  makes  silver  nicer  to  vise  than  cheaper  metals  ? 
How  can  plates  of  copper  be  coated  with  plates  of  silver  ?  How 
can  a  thin  covering  of  silver  be  given  to  a  thing  made  of  another 
metal  by  dint  of  mercury  ?  How  is  the  mercury  got  rid  of?  (Do 
not  ask  any  questions  about  electro-plating.) 


XXIX. 

Steel,  Tempering,  Pewter,  Enamel,  Borax 

Things  to  be  Seen — Pieces  of  cast  iron,  wrought  iron, 
and  steel — an  air-gas  burner,  or  flame  of  burning 
spirits  of  wine— some  water — 'pewter — tin — lead — 
antimony — copper — ground  flints  —  borax  —  soda — 
poivdered  glass — an  enamelled  iron  pot. 

§  80.  Steel. — Steel  is  made  from  cast  iron  in  two 
ways.  In  the  first,  the  cast  iron  is  made  wrought  iron  in 
the  way  described  in  §  16,  and  while  hot  and  soft,  passed 
between  two  rollers,  having  each  a  groove  cut  round  it. 
In  this  way  the  iron  is  squeezed  into  the  shape  of  a  bar. 
These  bars  are  cut  into  lengths,  and  buried  in  charcoal  in 
an  earthenware  pot  called  a  crucible,  and  the  whole  is 
heated  red-hot  for  several  days.  The  carbon  of  the  char- 
coal gradually  soaks  into  the  iron  and  changes  it  into  steel. 
The  action  is  stopped  before  too  much  carbon  has  got  into 
the  iron.  For  the  difference  between  wrought  iron,  steel, 
and  cast  iron  is  chiefly  this,  that  wrought  iron  contains  little 
or  no  carbon  or  silicon,  steel  contains  some  carbon  and  no 
silicon,  and  cast  iion  more  carbon  and  silicon.  So  that  if 
too  much  carbon  entered  the  iron,  we  should  go  back 
nearly  to  cast  iron  again.  Another  way  is  to  blow  air 
through  the  melted  cast  iron,  and  so  burn  off  so  much 
carbon  and  silicon  that  the  metal  contains  scarcely  any, 


STEEL,  PEWTER,  ENAMEL.  83 

then   to    add   a   little    iron,  -which   is  combined   with   a 
large  quantity  of  carbon,  so  as  to  make  the  mixture  right. 

§  81.  iSteel,  when  heated  red-hot  and  suddenly  cooled, 
becomes  exceedingly  hard  and  brittle.  The  less  hot  it  is 
when  suddenly  cooled,  the  less  hard  and  brittle.  So  that  we 
may  get  steel  of  any  hardness  in  two  ways — either  by  heating 
cold  soft  steel  to  a  given  temperature  and  cooling  it  sud- 
denly, or  by  hardening  it  first  as  hard  as  possible,  then 
heating  it  to  a  given  temperature  and  suddenly  cooling  it 
in  water.  The  latter  plan  is  that  generally  followed  ; 
because,  when  hard  steel  is  heated  to  different  degrees,  its 
surface  becomes  coloured  differently — that  is,  the  colours 
change  with  the  temperature — so  that  one  amount  of 
hardness  is  always  got  on  suddenly  cooling  the  metal  when 
it  shows  a  particular  colour.  This  is  called  Tempering 
the  steel. 

§  82.  Pewter. — Pewter  is  an  alloy  or  mixture  of  tin 
and  lead,  or  tin,  a  little  antimony,  and  copper.  Pewter 
is  used  for  plates  and  dishes,  and  for  beer  pots. 

§  83.  Enamel. — Iron  pots  which  are  used  in  cooking 
are  often  coated  inside  with  a  hard  white  stuff  called 
enamel.  This  prevents  the  iron  from  rusting,  and  from 
being  attacked  by  the  juice  of  the  food,  which  is  often  . 
acid.  The  enamel  is  made  of  two  parts,  the  white  body 
of  the  enamel  and  a  transparent  glaze.  Pots  may  be 
enamelled  as  follows  : — The  pot  having  been  thoroughly 
cleaned  by  weak  sulphuric  acid  (see  §  127)  and  water,  and 
washed  and  dried,  is  covered  on  the  inside  with  a  paste 
made  of  ground  flints  and  Borax.  Eorax  is  borate  of 
soda — that  is,  it  is  the  union  of  the  three  elements,  boron, 
sodium,  and  oxygen.  Borax  is  found  in  China,  Ceylon, 
California,  and  South  America,  and  looks,  when  pure, 
very  like  washing-soda,  and  is,  indeed,  sometimes  used 
instead  of  that  substance  for  washing  clothes.  The  paste 
of  borax  and  powdered  flint  is  allowed  to  dry  on  the 
metal.  This  will  form  the  body  of  the  enamel.  To 
get  the  glaze,   the    surface    is    covered  with    a    powder 


84     ENAMEL,  POTTERY,  CROCKERY,  EARTHENWARE. 

made  of  borax,  washing-soda  (see  §  120),  and  powdered 
white  glass  (see  §  27) ;  this  will  form  the  glaze.  The  pot 
with  its  two  coatings  is  now  heateff  in  an  oven,  so  that 
the  frame  of  the  fire  cannot  actually  reach  the  pot,  till  the 
coatings  soften. 

Questions. — How  is  steel  made  from  wrought  iron  ?  What  is  the 
difference  between  wrought  iron,  cast  iron,  and  steel  ?  How  can 
steel  be  made  from  cast  iron  without  first  making  the  cast  iron  into 
wrought  iron  ?  How  can  steel  be  made  very  hard  and  brittle  ? 
How  can  very  hard  steel  be  made  less  hard  ?  How  can  soft  steel 
be  made  as  hard  as  you  please  ?  What  is  "  tempering"  ?  What 
is  pewter  made  of  ?  AVhat  is  it  used  for  ?  What  is  the  use  of 
enamelling  iron  pots  ?  What  is  enamel  made  of  ?  What  is 
borax?     What  is  glaze  made  of ? 


XXX. 

Pottery,  Crockery,  Earthenware,  Porcelain, 
Felspar. 

Things  to  be  Seen. — Pipe-clay  —  Cornish  clay  —  any 
other  hinds  of  clay — flint— ground  flint — drawing  of 
potter's  loheel — felspar — different  kinds  of  pottery — 
crockery — earthenware — porcelain. 

§  84.  Pottery,  Crockery,  Earthenware. — All  these 
are  made  of  much  the  same  things,  although  they  look  so 
different.  "When  pure  clay  is  baked,  it  shrinks  and  warps 
a  good  deal ;  this  does  not  much  matter  for  bricks  and 
tiles,  but  it  won't  do  for  cups,  saucers,  plates,  and  so  on. 
To  make  such  shrinking  less,  the  clay  is  mixed  with 
ground  flint  —  that  is,  silica.  The  flints  are  washed, 
heated  red-hot,  and  thrown  into  water.  This  makes  them 
crumbly.  They  are  crushed  and  sifted,  and  the  powder 
is  ground  between  hard  stones  with  water.  Then  it  is 
stirred  in  water,  and  the  coarser  grains  allowed  to  settle. 
The  milky  liquid  is  mixed  with  clay  cleaned  in  the  same 
way,  the  water  is  driven  off  by  heat,  and  the  paste 
kneaded  together.  A  little  "  China  clay,"  or  "Cornish 
clay " — that  is,  granite  which  has  been   acted  on   for  a 


EARTHENWARE,  PORCELAIN.  85 

long  time  by  air  and  water,  and  so  got  softened — is  added, 
and  the  clay  is  then  either  pressed  into  moulds  of  the 
shape  wanted,  or  puVon  a  little  table  which  turns  round, 
called  a  "  potter's  wheel,"  and  fashioned  by  the  hand  as 
it  turns.  The  shape  is  made  very  true  by  holding  up 
against  the  turning  clay  an  edge  cut  into  the  .shape  of  the 
outline  of  the  vessel  which  has  to  be  made. 

The  pieces  of  crockery  are  next  gradually  dried,  and 
then  baked  in  ovens  or  kilns  like  brick-kilns  (see  §  5). 

§  85.  Porcelain  is  not  the  same  as  common  crockery; 
because,  besides  the  clay  and  silica,  it  has  some  potash. 
This  is  got  into  it  by  mixing  the  clay  Avith  Felspar, 
which  is  one  of  the  things  which  make  granite  (see  §  11) ; 
but  sometimes  whole  rocks  are  made  of  nearly  pure 
felspar. 

Felspar  contains  only  clay  (that  is,  silica  and  alumina) 
and  potash.  The  felspar  melts  at  a  lesser  hotness  than 
clay,  and  so  binds  the  other  things  together,  and  makes 
them  more  transparent — that  is,  more  easily  seen  through 
— when  cold  and  hard. 

Felspar  is  used  to  give  a  face  or  hard  smooth  skin  to 
the  finer  kind  of  crockery — that  is,  to  glaze  it,  just  as  salt 
is  used  to  glaze  such  things  as  drain-pipes  (see  §  6).  But 
while  salt  goes  off  as  a  gas,  and  so  touches  the  things  in 
the  kiln  which  were  near  it,  felspar  does  not  do  so,  and 
so,  to  glaze  a  thing  by  felspar,  the  felspar  is  powdered  and 
made  with  water  and  vinegar  (I  do  not  know  the  use  of 
the  vinegar)  into  a  sort  of  cream,  into  which  the  porcelain 
things  are  put  before  baking. 

Questions. — What  are  pottery,  crockery,  and  earthenware  made 
of?  How  is  the  shrinking  of  the  clay  on  baking  lessened  ?  How 
is  the  Hint  powdered  ?  What  is  China  or  Cornish  clay  ?  What  is 
a  potter's  wheel,  and  how  is  it  used  ?  What  is  the  difference 
between  porcelain  and  crockery  ?  What  is  felspar  made  of?  Why 
is  it  used  in  making  porcelain  ?  '  How  is  felspar  used  to  glaze 
crockery  ? 


PART    VI. 


CLOTHING. 

XXXI. 

Broad-cloth,  Fuller's  Earth,  Fulling,  Teasel,  Felt. 

Things  to  be  Seen. — Different  hinds  of  broad-cloth — 
Fuller's  earth — fulling  teasel — pieces  of  felt. 

§  86.  Broad-cloth. — The  shorter  fibres  of  the  sheep's 
wool,  such  as  those  which  grow  under  the  neck,  together 
with  the  short  fibres  which  are  separated  by  combing,  are 
used  for  broad-cloth.  These  are  spun  and  woven  as 
before  described  (see  §  70).  To  get  rid  of  the  oil  with 
which  the  wool  was  oiled,  and  otherwise  to  clean  it,  the 
web  is  beaten  about  under  water  with  a  kind  of  smooth 
soft  clay  called  Fuller's  Earth.  This  is  called  Fulling. 
It  is  then  shrunk  by  being  steeped  in  hot  and  cold  water 
repeatedly,  and  is  then  nailed  upon  a  frame  to  dry.  The 
next  thing  is  to  raise  a  "  nap" — that  is,  while  leaving  the 
body  of  the  web  unchanged,  to  pull  out  the  ends  of  the 
fibres  without  breaking  them.  This  is  done  by  rubbing 
the  cloth  with  the  heads  of  a  kind  of  thistle  called  the 
Fuller's  thistle,  or  Teasel.  The  spikes  on  the  head  of 
the  teasel  carry  little  hooks.  The  thistle-heads  are  fixed 
in  a  flat  square  frame,  and  the  web  is  brushed  with  it. 
Brushes  are  sometimes  used  for  this  purpose,  the  hairs  of 
which  are  pieces  of  steel  wire  with  little  hooks  at  the 
end.  The  teasel-frame  is  moved  both  across  the  cloth  and 
lengthways,  so  as  to  pull  out  the  ends  of  the  fibres  both 


BROAD-CLOTH,  FELT.  87 

of  the  warp  and  the  woof.  The  cloth  so  scratched  has  a 
nap,  but  it  is  very  uneven,  some  hairs  being  longer  than 
others.  It  is  cut  even  by  being  pressed  against  a  very 
narrow  moving  knife-blade.  This  blade  is  wound  like  a 
screw  upon  a  roller,  so  that  when  the  cloth  is  held  against 
it,  the  nap  is  cut  just  as^  the  grass  is  cut  by  a  lawn-mowing 
machine.  Finally,  the  cloth  is  folded,  and  between  each 
fold  is  a  sheet  of  glazed  paper  ;  the  whole  is  then  pressed, 
and  the  paper  taken  out ;  this  makes  the  surface  glossy. 
Broad-cloth  is  chiefly  used  for  clothes. 

§  87.  Felt. — Felt  is  made  by  tangling  fibres  together 
into  a  kind  of  mat.  Instead  of  laying  and  combing  the 
fibres  side  by  side  and  twisting  them  into  threads  (silk, 
linen,  worsted,  cotton),  and  then  weaving  the  threads 
together  so  as  to  make  a  web,  the  fihres  are  torn  to  pieces 
and  cast  into  the  air,  so  as  to  fall  anyhow  in  direc- 
tion, but  so  that  they  make  a  layer  of  even  thickness. 
Such  a  layer  is  rubbed  on  a  table  with  coarse  woollen 
cloth  until  the  fibres  tangle.  To  increase  the  thickness, 
one  can  either  add  more  fibres  and  rub  them  in,  or  make 
a  new  thin  felt  and  rub  it  on  the  top  of  the  first  until 
their  fibres  lock  together. 

Felt  can  be  made  out  of  most  kinds  of  hair  or  wool. 
It  is  used  for  hats.  When  made  of  coarse  fibres  and 
covered  with  tar,  it  makes  a  good  light  waterproof 
covering  for  roofs.  It  is  more  springy  than  woven  webs, 
so  that  it  is  often  used  for  covering  floors.  The  fibres  are 
short,  so  that  unless  they  are  bound  together  by  some- 
thing sticky,  felt  is  dusty  and  wears  away. 

Questions. — How  is  the  oil  got  out  of  the  woven  woollen  web  ? 
What  is  Fuller's  earth  ?  How  is  the  cloth  shrunk  ?  What  is  the 
nap  of  cloth  ?  How  is  it  got  ?  How  is  it  made  even  ?  How  is  the 
face  of  cloth  made  glossy  ?  What  is  felt,  and  how  is  it  made  i 
What  is  felt  used  for  / 


88  SILK. 


XXXII. 

Silk,   Satin,    Velvet,   Velveteen,   Fustian,   Serge, 
Kerseymere,  Merino,  Crape,  Alpaca,  Straw. 

Things  to  be  Seen. — A  silk  cocoon  and  draivings  of  silk- 
worm, chrysalis,  and  moth — floss-silk — silk  thread — 
woven  silk — satin — velvet — velveteen — fustian — serge — 
kerseymere — crape — alpaca — merino — straw. 

§  88.  Silk. — A  moth  lays  eggs  which  hatch  in  warm 
weather,  and  out  of  each  egg  comes  a  little  caterpillar 
called  a  silk-worm.  This  feeds  on  leaves,  and  grows,  and 
when  it  has  stopped  growing,  it  presses  out  of  its  body, 
through  two  little  holes  in  its  head,  a  sticky  juice,  which 
hardens  quickly  in  the  air.  The  first  of  this  is  stuck  by 
the  caterpillar  on  some  solid  body,  and  by  moving  the 
head  away  more  is  drawn  out,  and  so  on.  In  this  way 
the  caterpillar  winds  around  itself  an  unbroken  double 
thread,  making  thus  a  case,  in  the  form  of  an  egg,  about  as 
big  as  a  walnut.  This  is  called  a  cocoon,  and  is  Silk.  Then 
the  caterpillar  turns  into  a  chrysalis  inside  the  cocoon.  The 
chrysalis  is  like  a  large  maggot.  It  has  no  legs  ;  it  has  a 
hard  skin.  When  left  to  itself  in  the  cocoon,  the  chrysalis 
changes  into  a  moth,  and  the  moth  forces  its  way  out  of 
the  cocoon,  lays  eggs,  and  dies.  In  getting  out  of  the 
cocoon  the  moth  breaks  the  fibres.  To  prevent  this, 
when  long  fibres  are  wanted,  the  cocoon  is  put  into  an 
oven  or  hot  Avater,  or  set  out  in  the  strong  sunshine, 
which  kills  the  chrysalis.  Some  cocoons  are  kept,  and 
the  chrysalis  is  allowed  to  become  a  moth,  and  the  moth  is 
allowed  to  come  out  and  lay  eggs.  The  silk  of  such  cocoons, 
together  with  the  outside  parts  of  all  cocoons,  are 
collected,  and  form  what  is  called  Floss-silk.  The 
inside  parts  of  the  cocoons  in  which  the  chrysalis  has 
been  killed  are  soaked  in  warm  water,  to  soften  the 
gummy  stuff  which  sticks  the  threads  together ;  and  the 
ends  being  picked  up  from  several,  the  threads  are  wound 


SATIN,  VELVET,  ETC.  89 

off,  twisted  together,  dried,  and  wound  on  large  wheels. 
The  floss-silk  is  served  much  in  the  same  way  as  cotton 
(see  §  54). 

§  89.  Satin. — Satin  is  silk  woven  in  such  a  way  that  the 
weft  thread  passes  over  several  neighbouring  warp  threads, 
then  dives  under  only  one,  then  passes  over  several  again, 
and  so  on  ;  so  that  most  of  the  weft  thread  is  above  the 
warp.  This  gives  a  very  smooth  upper  face  to  the  web ; 
but  the  two  faces  are  not  alike. 

§  90.  Velvet. — If  the  loops  of  the  weft  of  a  web 
woven  like  satin  are  cut  through,  and  the  ends  brushed 
up  and  made  even,  the  cloth  called  velvet  is  made.  To 
make  the  web  for  velvet,  flat  wires  are  woven  in,  and 
then  pulled  out,  and  a  knife  is  passed  through  where  the 
wires  were. 

§  91.  Velveteen. — Velveteen  is  cotton  woven  and  cut 
like  velvet. 

§  92.  Fustian. — Fustian  is  a  rougher  kind  of  velveteen. 

§  93.  Serge  and  Kerseymere. — Serge  and  kerseymere 
are  the  same  as  fustian,  only  made  of  wool.  Merino  is 
a  kind  of  sheep's  wool. 

§  94.  Crape. — Crape  is  made  of  thin  twisted  silk 
threads  woven  rather  open. 

§  95.  Alpaca. — Alpaca  is  the  hair  of  a  kind  of  sheep 
which  is  wild  in  Peru.     It  is  woven  alone  or  with  cotton. 

§  96.  Straw. — Straw  is  the  dried  stalk  of  the  wheat  or 
other  tall  grass.  The  wheat  is  pulled  up  by  the  root 
before  the  seeds  are  ripe,  and  stacked  in  mows  to  dry,  and 
then  exposed  to  the  weather  and  sunshine  to  partly 
bleach,  that  is,  whiten  it.  The  bleaching  is  finished 
first  by  exposing  the  straw  to  steam,  after  the  roots  have 
been  pulled  off,  and  then  to  the  fumes  of  burning 
sulphur.  It  is  finally  exposed  to  the  air  for  a  time,  and 
is  then  ready  for  use.  It  is  too  brittle  to  bear  twisting 
much,  but  when  not  too  dry  it  can  be  plaited.  For  finer 
kinds  of  straw-work  the  straws  are  split. 


90  LEATHER. 

Questions. — How  is  silk  brought  forth  ?  Whafr  is  a  cocoon  ? 
What  happens  to  the  silk-worm  after  it  has  made  the  cocoon  ? 
What  becomes  of  the  chrysalis  ?  Why  is  the  chrysalis  often  killed 
in  the  cocoon  ?  What  becomes  of  the  moth  if  it  gets  out  of  the 
cocoon  ?  What  is  floss-silk  ?  How  is  the  silk  got  from  the 
cocoon  ?  What  is  satin  ?  What  is  velvet  ?  What  is  velveteen  ? 
What  is  fustian  ?  What  is  serge  ?  kerseymere  ?  crape  ?  alpaca  ? 
What  is  straw  ?    How  is  straw  bleached  ? 


XXXIII. 

Leather,  Gelatine,  Tannin,  Tan,  Kid-skin,  Wash- 
leather,  Chamois  (Shamoy),  Blacking. 

Things  to  be  Seen. — A  piece  of  raw  dry  hide — slaked 
lime — glue — glue  dissolved  in  water — oak  bark — tan 
(that  is,  ground  oak  bark) — dubbin — soot — tallow — 
fish-oil — bran — alum — salt — white  of  egg — pumice- 
stone — wash-leather — ground  bone-ch  arcoal — sperm  oil 
— treacle  — vinegar — sulphuric  acid — gum-arabic. 

§  97.  Leather. — Leather  is  made  from  the  skins  and 
hides  (that  is,  thick  skins)  of  animals.  To  make  leather 
from  the  skins,  they  have  to  he  cleaned  and  tanned,  and 
then  curried.  As  skins  have  often  to  he  carried  a  long 
way  after  they  are  stripped  from  the  animal,  and  as  wet 
skins  soon  rot,  they  are  thoroughly  dried,  or  sometimes 
salted.  Such  skins  have  first  to  be  dressed  (that  is,  the 
horns,  tail,  and  thin  edges  cut  off),  and  then  thoroughly 
soaked  and  kneaded  in  water  to  make  them  soft ;  then 
they  are  stirred  about  with  water  containing  slaked  lime 
(see  §  3).  This  loosens  the  hair,  which  is  then  scraped  off. 
Next  the  lime  is  completely  washed  out  with  water,  and 
the  skin  is  put  on  a  wide  round  beam  with  the  flesh  side 
upwards.  Then  it  is  scraped  clean  from  fat  and  the 
larger  blood-vessels  and  bits  of  flesh  by  a  curved  scraper  ; 
then  the  skins  are  turned  over  and  scraped  heavily  on  the 
other  side,  to  squeeze  "out  as  much  fat  as  possible.  Skins 
so- treated  would  get  hard  when  dry.  They  have  next  to 
be  Tanned.      Skins  contain  a  large  quantity  of  a  sub- 


LEATHER.  91 

stance  calledrGELATiNE,  which  is  nothing  else  hut  glue 
(see  §  25) ;  hut  in  the  skin  this  gelatine  is  held  in  little 
hags,  just  as  the  fat  of  animals  is  held  (see  §  41).  This 
gelatine,  or  glue,  hecomes  quite  hard  when  it  is  mixed 
with  the  liquor  in  which  the  harks  of  some  trees  (such  as 
oak  and  willow),  or  the  wood  of  others,  have  been  steeped. 
The  reason  is,  that  such  harks  or  wood  contain  a  sub- 
stance called,  from  its  use,  Tannin,  and  which  can  be  got 
pure  as  a  white  powder,  which  dissolves  in  water.  This 
tannin  it  is  which  makes  the  gelatine,  and  so  the  skin,  hard 
and  less  acted  on  by  water.  The  gelatine  is  made  harder 
than  it  is  in  the  wet  skin,  but  not  so  hard  as  it  is  in  the  dry 
— not  so  hard  as  dry  glue.  To  tan  the  skins,  they  are 
thrown  into  a  pit  and  stirred  now  and  then  for  several  weeks 
with  water  and  chips  of  oak  bark.  At  last  they  are  laid 
in  a  pit  in  a  single  layer  on  a  layer  of  ground  oak  bark 
called  Tan.  More  skins  are  spread  on  this,  then  more 
tan,  and  so  on,  and  the  whole  is  covered  with  water  in 
which  tan  has  been  boiled.  Time  after  time  the  old  tan, 
called  spent  tan,  is  replaced  by  new,  and  in  about  a  year 
the  tanning  is  finished,  if  the  leather  is  thick  like  sole- 
leather — that  is,  if  the  skin  is  a  hide.  The  skins  are 
finally  scraped  and  rolled  under  a  heavy  brass  roller. 

Calf-skins  and  other  thinner  skins  are  tanned  in  the 
same  way ;  but  before  being  put  in  the  tan-pit  they  are 
kneaded  and  rubbed  for  some  days  with  manure. 

After  tanning,  the  leather  comes  into  the  hands  of  the 
Currier.  The  currier  damps  the  leather,  and  lays  it 
across  a  hoard  with  the  side  where  the  hair  used  to  be 
downwards.  He  then  pares- the  surface  away  by  means 
of  a  knife  having  a  handle  at  each  end,  and  having  the 
edge  of  its  blade  turned  round  like  a  hook.  By  this  tool 
the  leather  is  so  shaved  that  it  is  equally  thick  all  over? 
Next  the  leather  is  wetted  and  put  on  a  slate  table,  the 
side  where  the  hair  was  being  downwards,  and  scraped 
with  a  blunt  edge,  and  brushed  with  water  with  a  strong 
brush.     The  skin  is  turned  over,  and  the  hair  side  is 


92  KID-SKIN,  WASH-LEATHER. 

brushed  and  scraped  in  the  same  way,  to  remove  a  white 
substance  which  comes  from  the  tan.  When  it  has  been 
taken  from  the  table  and  hung  till  nearly  dry,  it  is 
painted  with  dubbin,  which  is  a  mixture  of  soot  or  lamp- 
black (carbon)  and  tallow  and  fish  oil.  As  the  leather 
dries,  the  greasy  mass,  especially  its  oil,  sinks  in. 

§  98.  Kid-skin,  as  used  for  gloves,  is  also  prepared  for 
tanning  something  in  the  same  way,  namely,  by  scraping 
and  liming ;  the  hair  is  plucked  out  by  tweezers,  and 
the  face  ground  by  a  flat  stone,  and  the  lime  is  washed 
out.  The  skins  are  then  left  for  some  weeks  in  a  mixture 
of  bran  and  water.  The  bran  ferments  (see  §  107),  and 
part  of  the  skin  ferments,  giving  off  carbonic  acid  from 
its  pores ;  this  opens  them.  Next  begins  the  process  of 
tanning.  The  skins  are  steeped  for  a  few  minutes-  in  a 
solution  of  alum  and  salt.  To  the  alum  and  salt  both 
flour  and  the  yolks  of  eggs  are  added,  so  as  to  make  a 
paste.  The  skins  are  kneaded  in  this,  and  left  in  it  for 
some  hours,  taken  out,  and  dried  for  a  week  or  two.  To 
finish  them,  they  are  dipped  in  water  and  rubbed  Avith  a 
smooth,  hard,  nearly  flat  tool ;  then  dried  and  stretched, 
smoothed  on  one  side  with  pumice-stone  (see  §  128), 
and  ironed  with  a  hot  iron. 

§  99.  Wash-leather,  or  Chamois  (Shamoy). — 
Wash-leather,  which  is  used  in  cleaning  glass  and  silver, 
is  made  much  in  the  same  way  as  kid,  but  from  stouter 
skins,  such  as  those  of  deer  and  of  sheep.  After  cleaning 
and  liming,  the  hair  side  of  the  skin  is  rubbed  off  with 
pumice-stone  (see  §  128).  The  skins  are  then  steeped 
in  bran-water  as  above,  and  washed  and  partly  dried, 
beaten,  and  washed  often  with  hsh  oil.  Then  they  are 
piled  together  for  a  time.  The  oil  is  removed  by  weak 
lye  (see  §§  119,  120),  and  the  skins  are  washed  and  dried. 

Leather  is  used  for  boots  and  shoes,  and  gloves  and 
riding-trousers ;  for  covering  chairs  and  sofas  ;  for  binding 
books  ;  for  some  kinds  of  aprons ;  for  harness,  straps, 
bags,  belts,  and  many  other  things. 


BLACKING,  FUR.  93 

§  100.  Blacking. — Blacking,  as  used  for  boots,  is 
generally  a  mixture  of  ground  bone-charcoal,  called  bone- 
black  (see  §§  38,  117),  with  sperm  oil  (see  §  47),  treacle 
(see  §  117),  vinegar  (see  §  118),  and  sulphuric  acid  (see  § 
127).  In  paste-blacking  there  is  less  vinegar;  sometimes 
gum-arabic  (see  §  139)  is  added.  The  use  of  good  black- 
ing keeps  boots  sound,  but  blacking  with  too  much 
sulphuric  acid  rots  them. 

Questions. — What  is  leather  ?  How  are  skins  and  hides  kept 
from  rotting  ?  What  is  meant  by  the  dressing  of  the  skins  ?  How 
is  the  hair  got  oft'  the  skins  ?  How  are  the  skins  further  cleaned  ? 
"What  is  gelatine,  and  how  does  it  lie  in  the  skins  ?  What  is 
tannin,  and  where  is  it  found?  What  is  the  action  of  tannin 
on  gelatine  ?  What  is  tan,  and  how  are  skins  tanned  ?  How 
are  calf-skins  tanned  ?  What  does  the  currier  do  to  the  skin  ? 
What  is  dubbin?  How  are  kid-skins  handled  before  tanning? 
How  are  they  made  porous  ?  How  are  they  then  tanned  ?  How 
is  wash-leather  made  ?  What  is  leather  used  for  ?  What  is 
blacking  made  of  ? 


XXXIV. 

Fur,   Combs,   Ebonite,   Pins,   Cream   of  Tartar, 
Tartaric  Acid,  Brooms,  Brushes,  Bast. 

Things  to  be  Seen. — Some  pieces  of  fur,  with  the  skin 
— lard — sawdust — plaster  of  Paris — pieces  of  tortoise- 
shell —  boxwood  —  ebonite  —  india-rubber — sulphur — 
pins — brass  wire — draw-plate,  or  drawing  of  one — 
cream  of  tartar — bran — birch  twigs — cocoa-nut  fibre — 
broom — bast  —  horse-hair  —  bristles  —  camel-hair,  or 
ermine  brushes. 

§  101.  Fur.- — Skins  dressed  with  their  fur  on  are 
ca]Jed  furs.  Such  skins  are  not  tanned.  The  back  of  the 
dry  fur-skin  is  rubbed  with  salt  butter  or  Lard — that  is, 
pigs'  fat — and  this  is  thoroughly  worked  in.  Then  the 
fur-skins  are  wetted  and  scraped,  just  as  the  skins  are 
treated  before  tanning.  To  remove  the  grease,  they  are 
kneaded  with  sawdust  and  then  with  plaster  of  Paris  (see 


94  FUR,  COMBS,  PIN!?. 

§  12).  After  beating  and  combing,  they  are  ready  for 
use.  Furs  are  used  in  cold  countries  for  clothing. 
Babbit-fur  is  used  for  men's  hats.  Many  kinds  are  i-sed 
for  trimming  women's  dresses,  for  muffs,  and  the  like. 
Sealskin  is  the  fur  of  the  seal,  from  which  the  long,  dark 
hairs  have  been  taken  off. 

§  102.  Combs. — Combs  are  simply  flat  pieces  of 
metal,  horn,  bone,  or  ivory,  or  the  shell  of  the  tortoise 
(Tortoise-shell),  or  boxwood,  or  Ebonite.  Ebonite  is 
India-rubber  (see  §  137)  which  has  been  heated  strongly 
with  a  large  quantity  of  sulphur  (see  §  49).  The  sulphur 
unites  with  the  india-rubber,  and  forms  with  it  a  hard 
brown  mass,  which  becomes  nearly  black  on  polishing. 
If  there  be  less  sulphur,  and  the  heating  be  not  so  strong 
and  not  so  long,  the  india-rubber  forms,  with  the  sulphur, 
a  body  known  as  vulcanised  india-rubber,  or  Vulcanite. 
This  is  very  elastic,  and  does  not  get  hard  with  cold,  as 
india-rubber  does,  nor  does  it  stick  together  like  that 
substance.  It  is  usad  for  tubes  and  elastic  bands.  The 
combmakers  cut  the  teeth  of  the  comb  by  means  of  two 
circular  saws,  as  far  apart  as  the  teeth  of  the  comb  have 
to  be.  One  of  these  saws  is  a  little  larger  than  the  other, 
so  that  when  the  plate  is  pressed  upon  them  one  cuts 
deeper  than  the  other.  The  plate  is  then  shifted  so  that 
the  larger  saw  finishes  the  first  slit  of  the  lesser  saw, 
while  the  lesser  one  is  making  a  fresh  slit,  and  so  on.  By 
this  means  it  is  clear  that  the  teeth  will  be  all  at  the 
same  distance  apart ;  for  the  big  saw  in  the  shallow  slit 
serves  as  a  guide  for  the  little  saw  to  begin  its  work. 
Clean  cut  surfaces  of  tortoise-shell  stick  perfectly  together, 
without  cement,  when  warm.  In  this  way  large  combs 
can  be  built  up.  The  rough  faces  and  edges  of  the  slits 
left  by  the  saw  are  smoothed  by  a  file  and  polished  w^th 
pumice-stone  powder  (see  §  128). 

§  103.  Pins. — Brass  wire  (see  §  20)  is  drawn  through 
holes  in  a  steel  plate  (a  Draw-plate),  until  it  has  the 
thickness  wanted.     It   is  straightened   by  being  drawn 


TINS,  BROOMS    AND   BRUSHES.  95 

between  six  or  seven  smooth  iron  pegs  set  upright  in  a 
table,  nearly  in  a  line,  some  distance  apart,  in  such  a  way 
that  the  wire  passes  on  one  side  of  one  peg  and  the  other 
side  of  the  other,  and  so  on.  Lengths  twice  as  long  as 
the  pin  has  -to  be  are  cut  off  with  a  chisel,  and  both  ends 
of  such  pieces  are  pointed  by  being  ground,  and  turned 
round  during  the  grinding  on  a  steel  wheel  which  turns 
round,  and  has  an  edge  like  the  face  of  a  file.  Another  steel 
wheel,  with  finer  cut  face,  finishes  the  pointing.  The 
length  of  wire  is  now  cut  into  two  in  the  middle.  The 
piece  of  wire  is  held  near  the  broad  end  by  some  steel 
jaws  having  a  little  smooth  hole  in  them  at  their  very 
edges,  just  where  they  clutch  the  wire.  A  little  hollow 
steel  cup  is  forced  upon  the  end  of  the  pin.  This 
squeezes  the  end  of  the  pin  and  makes  it  fill  both  hollows, 
and  so  gives  it  a  solid  head.  This  is  a  little  flattened  by 
a  blow  with  a  hammer  while  still  held  in  the  steel  jaws. 
The  pins  are  now  plated  with  tin.  This  is  done  by 
boiling  them  with  pieces  of  tin  and  Cream  of  Tartar. 
Cream  of  tartar  is  tartaric  acid  united  with  potash  (see 
§  119).  Tartaric  Acid  is  the  acid  which  is  in  grapes 
and  other  fruits,  and  which  is  got  in  the  making  of  wine. 
The  pins  are  next  dried  and  polished  by  being  shaken 
with  bran  (see  §  106). 

§  104.  Brooms  and  Brushes. — Brooms  for  sweeping 
wet  stones  are  generally  made  either  of  twigs  of  the  birch 
tree,  or  of  cocoa-nut  fibre  (see  §  72),  or  of  the  Broom  (a 
plant  growing  on  heaths,  with  a  yellow  flower  the  shape 
of  a  sweet  pea-flower),  or  of  the  veins  of  the  leaves  of 
some  palm  trees,  or  the  unseparated  fibres  of  the  flax  and 
hemp  plants,  called  Bast.  Strips  of  bast  roughly  woven 
together  are  much  used  for  packing  furniture  when  it 
is  moved.  Dry  dust  is  swept  from  floors  and  the 
ground  by  brooms  made  of  horse-hair.  Carpet-brooms 
are  generally  of  cocoa-nut  fibre  or  bast,  hearth-brooms 
of  horse-hair;  scrubbing-brushes,  boot-brushes,  black- 
lead-brushes    (used    for   rubbing   blacklead   upon   grates 


96  BRUSHES,    NEEDLES. 

to  keep  them  from  rust),  clothes-brushes,  tooth-brushes, 
hair-brushes,  and  some  painters'  brushes  are  made  of 
hogs'  bristles,  those  of  the  neck  and  back  being  the 
longest.  Dusting-brushes  are  sometimes  of  feathers. 
Some  brushes  used  by  painters  are  made  of  horse-hair, 
some  of  different  kinds  of  fur,  the  very  finest  being  made 
from  the  hair  of  the  camel  or  the  tail  of  the  ermine. 
Hat-brushes  are  made  of  horse-hair. 

Questions.- — How  are  furs  got  ready  for  use  ?  What  are  furs 
used  for  ?  Of  what  stuffs  are  combs  usually  made  ?  What  is 
ebonite  ?  How  are  the  teeth  of  combs  cut  ?  How  is  brass  wire  got 
to  the  right  thickness  for  making  pins  ?  How  is  the  wire 
straightened  ?  Into  what  lengths  is  it  cut  ?  How  are  the  pins 
pointed?  How  are  the  heads  of  pins  made?  How  are  the  pins 
covered  with  tin  ?  What  is  tartaric  acid  ?  How  are  the  pins 
dried  and  polished  ?  What  are  brooms  and  brushes  generally 
made  of  ? 


XXXV. 

Needles. 

Things  to  be  Seen. — Needles — draio-plate,  or  drawing 
of  one — oil — sand — emery — saicdust — soap —  bran — 
wash-leather. 
§  105.  Needles. — Steel  wire  having  been  drawn 
through  the  draw-plate  (see  §  103)  to  the  thickness 
wanted,  is  cut  into  pieces  a  little  more  than  twice  as  long 
as  the  needle  is  to  be.  These  are  straightened  by  being 
pressed  and  rubbed  in  little  troughs.  The  two  ends  are 
pointed  and  sharpened,  without  water,  on  grindstones, 
which  are  made  of  stone,  finer  and  finer  stones  being 
used.  The  doubly-pointed  wires  are  cut  in  two  in  the 
middle  by  a  pair  of  steel  shears.  They  are  then  laid  flat 
on  a  little  copper  tray,  so  that  their  points  rest  against 
the  raised  edge  running  along  one  side  of  the  tray,  while 
their  thick  ends  project  over  the  opposite  edge.  The 
thick  ends  are  cut  off  by  a  pair  of  steel  shears,  to  which' 
the  edge  of  the  tray  serves  as  a  guide.  The  thick  ends, 
where  the  eye  is  to  be,  are  laid  upon  a  block  of  steel,  and 


NEEDLES.  97 

hit  with  a  little  smooth  steel  hammer.  This  flattens 
them.  At  the  same  time  it  hardens  them.  They  have  to 
be  softened  before  the  eye  can  be  made.  They  are  there- 
fore heated,  and  allowed  to  cool  slowly  (see  §  80).  The 
flattened  end  is  laid  upon  a  block  of  steel,  and  a  steel 
punch  (a  short,  pointed,  but  not  sharpened  steel  rod)  is 
struck  with  a  hammer  first  on  one  side  of  the  needle,  and 
then  the  needle  is  turned  over,  and  the  punch  is  driven 
through  from  the  other  side.  A  hard  steel  wire  is  now 
thrust  through  the  eye,  and  the  needle  being  held  with 
its  head  on  a  leaden  block,  so  that  the  wire  is  level,  a 
blow  is  given  first  on  one  side,  and  then  on  the  other. 
This  smooths  the  hole,  and  makes  it  take  the  shape  of 
the  wire  in  it.  Next,  grooves,  or  little  gutters,  are  made, 
running  one  on  each  side  of  the  eye-end  of  the  needle. 
These  are  of  use  to  guide  the  end  of  the  thread  in  thread- 
ing the  needle.  These  grooves  are  made  either  by  a  file 
01  by  a  stamp.  The  heads  of  the  needle  are  rounded  by 
the  file.  The  needles  are,  in  this  stage,  soft.  They  have 
to  be  tempered  and  annealed  (see  §  80).  Heated  red-hot 
on  trays,  and  thrown  into  cold  water,  they  become  very 
hard  and  brittle.  They  are  again  heated  to  a  fixed 
iiotness,  oi  till  theii  colour  shows  that  they  have  the 
right  temper  (see  §  80).  To  smooth  them  and  polish 
them,  they  are  first  rubbed  amongst  one  another  with  oil 
and  sand,  or  emery  (see  §  130).  The  oil  and  rust  is  got 
rid  of  by  shaking  them  with  sawdust.  The  sawdust  is 
blown  away  in  a  sort  of  winno wing-machine  (see  §  10G). 
The  last  of  the  oil  is  washed  out  with  soap  and  water. 
They  are  again  dried  with  sawdust,  and,  finally,  are 
shaken  with  bran  (see  §  10G),  and  polished  by  hand  with 
wash-leather. 

Questions. — What  are  needles  made  of?  How  is  the  steel  wire 
got  to  the  right  thickness  ?  How  are  the  needles  pointed  ?  "What 
is  done  tc  the  thick  ends  before  the  eyes  are  made  in  them  ?  How 
are  the  eyes  made  ?  How  are  the  grooves  over  the  eye  made  ? 
How  are  the  needles  tempered?  How  are  they  smoothed  and 
polished  ? 

G 


PART    VII. 

FOOD. 

XXXVI. 

Bread,  Sheaves,  Chaff,  Winnowing,  Bran,  Bolting, 
Gluten. 

Things  to  be  Seen. — A  wheat-plant  bearing  its  ear  of 
seeds — rye,  oats,  barley,  all  as  seeds — chaff- — wheat- 
grains  free  from  chaff — draiuing  of  flour-mill — ichole 
meal  —  bran  — flour — potash — phosph  oric  acid — mag- 
nesia— lime — silica — iron-rust — sidph  uric  acid — soda 
— xvater — starch — gluten — sugar — gum. 

§  106.  Bread. — Most  bread  eaten  in  this  country  is 
made  of  wheat.  Bread  is  also  made  of  rye,  and  oats,  and 
"barley.  Iwill  describe  the  makingof  bread  from  wheat ;  the 
other  kinds  of  bread  are  made  in  very  much  the  same  way. 
In  about  seven  months  after  the  wheat  begins  to  grow,  it 
is  ripe.  After  cutting  close  to  the  ground,  it  is  collected 
in  Sheaves  (about  an  armful),  and  a  few  of  these  are 
piled  together  with  the  ears  of  grain  upwards.  This  is  to 
allow  the  grain  to  get  thoroughly  dry.  It  may  now  be 
stacked — that  is,  piled  together — and  kept  for  a  year  or 
two,  if  kept  dry.  Or  it  may  be  used  at  once.  The  wheat 
is  next  threshed — that  is,  beaten  with  a  flail,  which  is 
made  of  two  bars  of  wood  jointed  together  at  two  of  their 
ends.  The  wheat  is  spread  upon  the  threshing-floor,  and 
the  ears  are  banged  with  the  flail,  which  shakes  out  the 
grain  from  the  ear,  and  also  shakes  off  the  husk,  or 
Chaff.     The  stalk  and  empty  ear  being  taken  away,  the 


BREAD.  99 

grain  and  chaff  are  poured  together  from  some  height  while 
air  is  blown  upon  them.  This  blows  the  chaff  on  ono 
side,  and  is  called  Winnowing.  The  reaping  or  cutting 
of  the  standing  corn,  the  threshing,  and  the  winnowing 
are  now  often  done  by  steam  power. 

The  wheat  is  now  taken  to  the  mill,  and  ground 
between  two  large,  rough,  flat,  round  stones,  one  being 
fixed  and  the  other  turning  upon  it.  The  faces  of  these 
stones  are  cut  into  a  sort  of  rasp  or  file ;  the  stone  itself 
is  nearly  pure  silica.  The  grain,  when  put  into  the  mill,  is 
covered  with  a  skin  ;  this  is  so  thin  and  easily  bent  that 
it  escapes  being  ground  fine,  and  comes  out  with  the 
ground  grain.  It  is  Bran  ;  the  ground  grain  is  the  flour. 
The  mixture  of  the  two,  as  it  comes  from  the  mill,  is 
called  whole-meal.  What  is  properly  called  "  brown- 
bread  "  is  made  of  whole-meal.  For  whiter  bread  the 
bran  is  separated  by  passing  the  meal  through  two  or 
three  sieves  of  increasing  fineness ;  the  purest  flour  being 
that  which  comes  through  the  last  or  finest  sieve.  This 
sifting  is  called  Bolting.  There  is  very  little  difference 
between  bran  and  flour,  as  to  what  they  are  made  of. 
There  is  a  little  more*mineral  matter  in  bran  than  in 
flour.  In  a  hundred  pounds  of  wheat-flour  there  are 
about  eleven  pounds  of  water.  If  a  hundred  pounds  of 
wheat-flour  are  thoroughly  burnt,  there  are  left  about  two 
pounds  of  ash.  In  a  hundred  pounds  of  such  ash  there 
are  about  thirty  pounds  of  potash  (see  §  119),  fifty 
pounds  of  phosphoric  acid  (see  §  50),  twelve  pounds  of 
magnesia  (see  §  67),  three  pounds  of  lime  (see  §  3),  four 
pounds  of  silica  (see  §  29),  half-a-pound  of  oxide  of  iron, 
a  quarter  of  a  pound  of  sulphuric  acid,  and  a  quarter 
of  a  pound  of  soda.  The  proportions  of  these  things 
vary  according  to  the  nature  of  the  wheat  and  the  soil 
upon  which  it  is  grown.  The  part  which  is  driven  off 
and  burnt  away,  namely,  about  ninety-eight  pounds  out 
of  the  hundred  of  flour,  is  made  up  of  about  ten  pounds  of 
water,  seventy  of  starch  (see  §  125),  eleven  pounds  of 


100  BREAD,  FERMENTATION,  YEAST,  BARM. 

Gluten  (a  body  made  of  oxygen,  hydrogen,  carbon,  and 
nitrogen),  and  four  of  gum  (see  §  139);  the  remaining  five 
pounds  are  made  of  a  little  fat,  sugar,  and  a  body  like  the 
white  of  an  egg. 

Questions.—  "What  is  bread  made  from?  How  is  the  wheat 
gathered  and  dried  ?  How  is  the  grain  freed  from  the  straw  and 
ear  ?  How  is  the  grain  freed  from  chaff  ?  How  is  corn  ground  ? 
What  is  bran  ?  How  is  bran  got  away  from  the  flour  ?  What  is 
whole  meal  ?  How  much  water  is  there  in  a  hundred  pounds  of 
wheat-flour  ?  How  many  pounds  of  ash  are  left  when  a  hundred 
pounds  of  wheat-flour  are  burnt  ?  What  is  this  ash  made  of  ? 
What  are  the  substances  which  are  driven  off  or  burnt  when  the 
flour  is  heated  ? 


XXXVH. 

Fermentation,  Yeast,  Barm,  Glucose,  Dextrine, 

Leaven,  Crated  Bread,  Biscuits,  Oatmeal. 
Things    to    be   Seen. — Yeast,    or   a   drawing   of  yeast- 

plants — starch — gum — sugar — alcohol — bottle  of  soda- 
water — potatoes — bread — bicarbonate  of  soda — hydro- 
chloric acid — biscuits — oatmeal. 

§  106  (continued). — The  next  thing  to  be  done,  to  make 
the  flour  into  bread,  is  to  make  it  into  dough,  and  to  make 
the  dough  spongy — that  is,  full  of  hollows.  There  are 
three  chief  ways  of  doing  this. 

§  107.  Fermentation,  Yeast,  Barm. — There  is  a 
little  plant  called  Yeast,  which  is  so  small  that  you  can 
scarcely  see  a  single  plant  without  a  magnifying  glass. 
But  when  a  yeast-plant  finds  itself  in  contact  with  its 
proper  food,  it  gives  rise  to  other  yeast-plants  at  a  very 
great  rate.  The  proper  food  of  yeast  is  starch,  gum,  sugar, 
and  Glucose  (a  kind  of  sugar  found  in  grapes  and  other 
fruit).  As  the  yeast  grows,  it  changes  the  starch,  gum,  and 
sugar  first  into  Dextrine,  and  then  changes  the  dextrine 
into  carbonic  acid  (see  §§  3,  8,  31,  32)  and  alcohol  (spirits  of 
wine,  see  §§  68,  1 15) .  A  little  yeast  will  in  time  change  any 
amount  of  these  substances  into  carbonic  acid  and  alcohol, 
and   will   itself  increase   in   quantity.     Such  change  is 


FERMENTATION,  YEAST,  BARM.  101 

called  Fermentation.  To  get  yeast,  some  potatoes  are 
boiled,  peeled,  and  mashed  with  water,  flour,  and  yeast. 
If  kept  warm,  this  soon  begins  to  ferment.  It  gets  filled 
with  yeast-plants.  This  pasty  liquid  is  sometimes  called 
Barm.  Some  of  this  yeast  is  mixed  with  more  Hour  and 
water,  and  the  whole  is  again  allowed  to  ferment.  This 
is  seen  by  its  swelling,  owing  to  the  formation  of  carbonic 
acid  gas  within  it,  which  makes  hollows  in  it.  Then  it 
is  mixed  with  salt,  which  flavours  it,  and  checks,  but  does 
not  stop  further  fermentation.  Lastly,  it  is  mixed  with 
more  flour  and  water,  and  the  whole  thoroughly  kneaded 
together.  After  fermentation  has  gone  on  for  a  couple  of 
hours,  the  dough  is  made  into  the  form  of  loaves,  and 
baked.  It  is  then  bread.  The  heat  of  the  oven  kills  the 
yeast,  and  increases  the  size,  of  the  bubbles  of  carbonic 
acid,  and  drives  out  the  alcohol.  Yeast  is  also  the  cause 
of  fermentation  in  making  beer  (see  §  115),  and,  as  more 
yeast  grows  in  the  brewery  than  the  brewer  wants,  he  sells 
it  to  the  baker,  and  so  the  latter  may  save  himself  the 
trouble  of  making  a  ferment  with  potatoes.  A  small 
piece  of  fermented  dough,  if  not  kept  too  long,  will  start 
a  fresh  lot  of  dough.  Such  a  piece  of  fermented  dough  is 
called  Leaven.  Leaven,  however,  soon  becomes  sour,  and 
makes  the  bread  so.  Large  quantities  of  yeast  are  im- 
ported in  a  compressed  state  from  the  German  breweries. 

§  108.  Another  way  of  making  bread  is  to  mix  the 
flour  with  a  little  bicarbonate  of  soda  (see  §  120),  and 
the  water  with  a  little  hyrochloric  acid  (see  §  120).  On 
making  the  dough,  the  acid  and  the  carbonate  give  rise  to 
water  and  chloride  of  sodium  (which  is  nothing  else  than 
common  salt),  and  carbonic  acid,  which  blows  out  the 
dough.  By  this  means  the  whole  of  the  flour  is  kept 
as  bread,  and  not  partly  spent  in  making  carbonic  acid 
and  alcohol,  and  there  is  so  far  an  advantage.  Some 
baking  powders  contain  an  acid  called  tartaric  acid. 
Such  baking  powders  are  not  wholesome  if  used  often. 

The  same  advantage  is  got  in  the  so-called  /E hated 


102  BISCUITS,  OATMEAL,  MILK. 

Bread.  If,  instead  of  water  to  mix  with  the  dough,  you 
were  to  use  soda-water — that  is,  water  into  which  carbonic 
acid  has  been  squeezed — and  if  you  could  mix  the  two 
into  a  dough  inside  the  soda-water  bottle,  then,  when  you 
took  the  dough  out,  the  carbonic  acid  would  blow  the 
dough  out  and  make  it  spongy,  just  as  fermentation  did. 
Machines  are  made  to  do  this,  and  the  dough  merely 
wants  baking  to  be  bread. 

§  109.  Biscuits.— Plaiu  biscuits  (such  as  ship  biscuits) 
are  simply  baked  unfermented  dough.  Fancy  biscuits  are 
made  by  adding  to  the  dough  such  things  as  starch,  sugar, 
treacle,  butter,  eggs,  and  various  spices  and  flavourings. 

§  110.  Oatmeal. — Oatmeal  is  generally  eaten  unfer- 
mented, either  as  oatmeal  cake,  which  is  the  meal  mixed 
with  water  or  milk,  and  baked  or  grilled,  or  as  porridge, 
which  is  the  meal  boiled  with  water  or  milk.  Most 
people  find  that  porridge  is  easy  to  digest.  Some  find 
it  more  wholesome  with  milk,  others  with  sugar,  others 
with  salt. 

Questions. — What  is  yeast  like?  What  does  it  live  on?  What 
does  it  change  its  food  into  ?  How  is  yeast  made  to  grow  ?  What 
is  barm  ?  How  is  the  dough  for  bread  made  ?  How  is  bread  made 
from  such  dough  ?  Whence  is  yeast  most  commonly  got  ?  What 
is  leaven  ?  What  other  way  is  there  of  making  the  bread  full  of 
little  hollows  of  carbonic  acid  ?  What  is  the  advantage  of  this  ? 
How  is  derated  bread  made  ?  What  are  biscuits  ?  What  is  done  to 
oatmeal  before  it  is  eateii  ? 


XXXVIII. 

Milk,  Cream,  Butter,  Cheese,  Whey. 

Things  to  be  Seen. — Fresh  milk — milk  xohich  has  stood 

a   few   hours,    showing    cream — butter — buttermilk — 

rennet  (or  hydrochloric  acid) — whey — cheese. 

§  111.    Milk. — The    milk    generally   used    either   for 

drinking  by  itself,  or  with  water,  tea,  and  coffee,  or  for 

making  butter  and  cheese,  is  the  milk  of  the  cow.     In 

some  countries  the  milk  of  the  ewe  goat,  camel,  mare,  or 


CREAM,  BUTTER,  CHEESE.  103 

reindeer  is  used.  Of  course,  as  young  animals  feed 
wholly  on  milk,  the  milk  they  drink  must  contain  every 
element  necessary  for  their  growth  except  oxygen,  which 
they  get  from  the  air.  The  chief  things  we  need  consider 
in  milk  is  the  fat,  which  gives  cream  and  butter ;  the 
substance  which  curdles,  called  curds,  which  gives  cheese; 
and  the  watery  part,  or  whey,  which  contains  a  kind  of 
sugar  and  mineral  bodies. 

§  112.  Cream. — Fresh  milk  is  a  yellowish-white 
liquid.  You  cannot  see  through  it,  because  there  are 
floating  in  it  numbers  of  very  small  drops  of  fat.  On 
standing,  these  rise  to  the  top,  and  form  a  layer  which  is 
skimmed  off,  and  is  cream ;  the  rest  of  the  milk  is  skim- 
milk.  Sometimes  the  milk  is  heated  (but  not  boiled)  to 
help  the  cream  to  rise. 

§  113.  Butter.— On  beating  the  cream  with  the  hand, 
or  in  a  kind  of  tub  called  a  churn,  the  buttermilk  which 
is  still  in  the  cream  is  squeezed  out  from  between  the 
drops  of  fat,  so  that  these  drops  touch  and  stick  to  one 
another.  When  they  do  so,  they  form  butter.  Instead  of 
letting  the  cream  rise  and  churning  it,  the  milk  itself 
is  often  churned,  and  the  butter  is  so  made  at  once, 
leaving  the  buttermilk. 

§114.  Cheese. — If  you  put  any  acid  to  unskimmed 
milk  a  part  of  the  milk  curdles — that  is,  it  turns  into  a 
kind  of  white  jelly,  called  Curds.  The  rest  of  the  milk 
is  then  called  Whey.  It  is  almost  as  clear  as  water. 
The  curds  contain  the  cream  (therefore  the  butter)  and  a 
substance  called  caseine,  or  cheese-stuff.  You  must 
understand  that  when  the  acid  is  added  to  the  milk,  it  is 
this  cheese-stuff  which  becomes  solid,  and  that  the  cream 
joins  it  in  becoming  solid.  If  you  take  this  solid,  and 
let  the  whey  drain  away  from  it,  you  get  what  is  called 
cream-cheese.  If  you  press  the  whey  out,  and  let  the 
stuff  turn  sour  (unite  with  the  oxygen  of  the  air)  and  rot 
(become  a  little  garden  of  plants  and  animals),  you  get 
ripe  cheese. 


104  CHEESE. 

Such  cheese  therefore  contains  all  the  cream  of  the 
milk.  But  suppose  you  first  take  the  cream  away,  and 
add  the  acid  to  the  skim-milk,  it  will  still  curdle,  but  the 
curds  will  not  contain  the  fat.  You  thus  get  a  curd,  and 
so  a  cheese,  which  you  may  call  poor,  if  you  call  fat  rich. 
Sometimes  the  fat  of  one  milk  (that  is,  the  cream)  is  put 
with  another  lot  of  milk  and  then  curdled.  In  tins  way 
such  cheeses  as  Stilton  and  "  double  "  cheeses  are  made. 
The  caseine,or  cheese-stuff, contains  a  great  deal  of  nitrogen. 
So  do  we.  And  we  get  all  the  nitrogen  from  our  food  (not 
directly  from  the  air,  although  it  contains  so  much — see 
§  30).  Flesh  (lean  meat)  contains  a  large  quantity  of 
nitrogen,  true  fat  none.  It  comes  then,  to  this,  that 
cheeses  made  from  whole  milk,  or  milk  to  which  cream 
has  been  added,  are  useful  to  those  whose  bodies  require 
fat.  Those  cheeses  which  have  been  made  from  skim- 
milk  are  useful  to  those  whose  bodies  require  flesh, 
always  supposing  that  the  same  weight  is  eaten  of  each 
kind. 

I  said  above  that,  in  the  making  of  cheese,  any  acid 
would  cause  the  milk  and  skim-milk  (not  the  pure  whey) 
to  curdle.  Different  acids  have  this  power  in  different 
degrees.  In  some  countries  the  acid  called  hydrochloric 
acid  (see  §  120)  is  used.  Cows  give  most  milk  soon 
after  having  calves,  and  the  stomach  of  the  calf  has  the 
power  of  curdling  milk  with  great  ease.  The  inner  skin 
of  a  calf's  stomach  is  cleaned,  salted,  and  dried,  and  is 
then  called  Rennet.  When  wanted  for  curdling  milk, 
pieces  of  rennet  are  soaked  in  water  and  added  to  the 
warm  milk.     The  whole  matter  stands  thus  : — 

Milk  consists  of  cream,  cheese-stuff  (caseine),  and  whey. 

Cream,  beaten,  becomes  butter. 

Cheese-stuff,  curdled  and  pressed,  and  allowed  to  rot, 
with  or  without  cream,  becomes  cheese. 

Whey  contains  almost  all  the  water  of  the  milk,  and  also 
a  particular  kind  of  sugar  called  milk-sugar,  and  some 
mineral  bodies. 


BEER.  105 

Questions. — From  what  animals  is  milk  got  ?  How  is  it  that 
very  youug  animals  need  nothing  for  food  but  milk?  How  is 
cream  got  from  milk,  and  what  sort  of  stuff  is  it?  How  is  butter 
made  from  cream  and  milk?  How  are  curds  got  from  milk? 
What  is  whey?  When  whole  milk  is  curdled,  what  becomes  of 
the  cream  ?  How  can  milk  be  curdled  ?  How  is  cheese  made 
from  curds  ?  What  is  the  difference  between  cheese  made  from 
whole  milk  and  cheese  made  from  skim-milk  ?  What  are  double 
cheeses?  What  is  rennet?  How  is  it  used?  What  is  cream 
made  of?     What  is  cheese  made  of ?     What  is  whey  made  of ? 


XXXIX. 

Eeer,  Sprouting  or  Germination,  Malt,  Mashing, 

Mash,  Grains,  Wort,  Hops. 
Things  to  be  Seen. — Barley  seed — sprouting -barley 
fcai'ed  malt  J — dried,  malt — wort  and  grains — hops — 
drawing  of  yeast  plant — alcohol — carbonic  acid  (as 
from  a  bottle  of  beer  or  ginger-beer ). 
§  115.  Beer. — The  grain  called  barley  is  generally 
used  for  making  beer — that  is,  ale,  porter, .  and  stout. 
The  ripe  grain  is  soaked  in  water  for  a  couple  of  days, 
then  drained  and  spread  in  shallow  heaps.  After  a  time, 
the  grain  begins  to  grow — lhat  is,  to  send  out  a  little 
shoot,  which  would  form  the  new  plant  if  earth  were 
present  (see  §  34).  During  this  shooting,  sprouting, 
or  "  Germination,"  as  it  is  called,  a  little  of  the 
starch  (see  §  125)  which  is  in  the  grain  is  turned  into 
glucose  (see  §  107),  and  the  sprouted  grain  in  this  state  is 
called  Malt.  The  malt  is  next  heated  on  a  floor  called  a 
malt-kiln.  This  stops  the  further  growth,  and  gives 
colour  to  the  malt,  and  so  to  the  beer  which  is  made  from 
it.  The  temperature  is  lowest  for  pale  ales,  and  highest 
for  stouts  and  porters.  The  kiln-dried  malt  is  next  sifted 
on  a  sieve,  which  lets  the  little  germ-stalks  only  pass 
through. 

The  malt  is  next  mixed  with  warm  water,  and  left  for 
a  little  while — whereupon  most  of  the  starch  is  changed 
into  glucose.     The  glucose  and  colour  dissolve ;  the  rest 


106  BEER. 

of  the  starch  is  softened,  and  little  else  is  left  in  the  seed 
but  gluten  (see  §  106).  The  boiling  and  stirring  of 
the  malt  with  water  is  called  Mashing.  The  Mash  is 
next  drained.  The  barley  which  has  thus  sprouted, 
and  been  dried  and  boiled  with  water,  is  called 
Grains  ;  the  part  which  is  drained  off,  and  which  con- 
tains glucose,  starch-matter,  and  some  of  the  minerals  of 
the  grain,  is  called  Wort.  The  next  thing  to  be  done  to 
make  the  wort  into  beer  is  to  give  it  a  bitter  flavour,  and 
to  prevent  it  turning  mouldy.  Both  of  these  ends  are 
gained  by  boiling  hops  in  it.  Hops  are  grown  for  this 
purpose.  The  hop-plant  is  a  trailing  or  climbing  plant, 
which,  when  cultivated,  is  made  to  grow  up  poles.  The 
flowers  are  gathered,  dried,  and  packed  in  sacks,  and  sent 
to  the  brewers,  who  boil  them  with  the  wort. 

Thus  flavoured  with  hops,  the  wort,  if  left  to  itself, 
begins  to  Ferment.  Placed  in  a  tub,  the  gas  is  formed  in 
it,  which  is  called  carbonic  acid  gas,  and  at  the  same  time 
alcohol  is  formed.  In  fact,  this  is  what  takes  place  : — ■ 
The  wort  contains  glucose,  and  this  glucose,  during  fer- 
mentation, divides  itself  into  two  parts,  one  of  which 
is  carbonic  acid,  and  the  other  is  Alcohol.  Alco- 
hol is  a  union  of  carbon,  oxygen,  and  hydrogen. 
(Spirits  of  wine  is  alcohol  and  water.)  But  when  this 
division  is  taking  place,  it  is  seen  that  the  liquid  becomes 
muddy,  and  it  is  found  that  a  sort  of  scum  rises  to  the 
top  of  the  worts  which  are  fermenting.  This  scum  is 
yeast,  and  this  yeast  is  the  same  as  that  used  in  making 
bread  (see  §  107).  A  little  of  this  yeast  put  into  fresh 
wort,  at  the  proper  temperature,  sets  it  fermenting — that 
is,  sets  more  of  these  yeast-plants  growing  ;  so  that  when 
one  quantity  of  wort  has  done  fermenting,  there  has  been 
born  a  very  great  number  of  yeast-plants,  which  can 
be  used  in  other  fermentations  (see  §  107).  Beer, 
therefore,  is  a  liquid  consisting  chiefly  of  water,  but  con- 
taining also  alcohol,  and  carbonic  acid,  and  colouring 
matter,  and  some  unaltered  glucose,  with  some  of  the 


SALT,  TABLE  SALT.  107 

mineral  matter  of  the  barley  and  the  bitterness  of  the 
hop. 

Questions. —  From  what  plant  is  beer  made  ?  How  is  barley  made 
to  sprout  ?  What  is  sprouted  barley  called?  What  is  a  malt-kiln  ? 
What  is  the  difference  between  ale  and  porter  ?  How  are  the  germ- 
stalks  got  rid  of?  "What  happens  when  the  malt  is  stirred  with 
warm  water  ?  What  is  mash  ?  What  are  grains  ?  What  is  wort  ? 
What  kind  of  plant  is  hop  ?  How  are  hops  used  for  beer,  and  why  are 
they  used  ?  What  is  fermentation  ?  What  gas  and  what  liquid  are 
formed  by  fermentation  ?  What  is  alcohol  made  of?  What  is  the 
scum  which  rises  to  the  top  of  fermenting  wort  ?  What  is  brewers' 
yeast  used  for  besides  making  wort  ferment  ?  What  is  beer  made 
of? 


XL. 

Salt,  Table  Salt,  Sugar,  Treacle,  Molasses, 
Vinegar. 

Things  to  be  Seen. — Salt — sugar-cane,  or  drawing  of 
one — beet-root — lime — bone-charcoal — treacle  —  brown 
sugar — loaf-sugar — sour  beer — vinegar. 
§  116.  Salt,  Table  Salt. — How  rain  falling  on  the 
earth  as  pure  water  gradually  dissolves  and  carries  down 
to  the  sea  some  of  the  things  which  it  meets  with  in  its 
course  has  been  described  in  §  5.  Also  in  §  8  has  been 
described  how  carbonate  of  lime  and  silica  were  solidified 
by  animal  life,  and  sent  down  as  shells. and  skeletons  to 
the  bottom  of  the  sea.  The  sea  is  made  of  water  and 
what  is  dissolved  in  the  water  ;  and  to  find  out  what  is 
in  the  sea  besides  water,  all  that  we  have  to  do  is  to  let 
the  water  pass  off  into  the  air,  that  is,  to  take  some  sea 
water  and  let  it  dry.  As  it  becomes  nearly  dry,  little 
bright  grains  appear — these  are  common  salt.  And  so 
common  salt  is  got  from  the  sea,  either  by  boiling  the 
water  away  or  by  allowing  the  sea-water  to  dry  up. 
Remember  there  are  many  other  things  in  the  sea  besides 
common  salt ;  and  if  you  were  to  dry  the  sea-water  quite 
dry  you  would  get  them  all  mixed.  But  it  happens  that 
as  you  dry  sea-water,  common  salt  is  the  first  of  those 


108  SALT,  SUGAB. 

things  to  become  solid.  In  many  places,  in  different 
countries,  the  sea  has  dried  up  gradually,  and  the  result 
is  that  in  such  places  there  are  great  masses  of  solid  salt, 
called  rock-salt,  which  have  got  covered  with  clay  and  other 
earth  (see  §  5).  This  salt  is  sometimes  so  pure  that  it  can 
be  cut  out  with  a  pick  and  sold.  More  generally  it  has  to 
be  dissolved  in  water  and  strained,  or  allowed  to  settle,  so 
that  clay  and  other  dirt  may  sink  down ;  it  is  then  boiled, 
to  drive  off  the  water.  As  the  solid  salt  separates,  it  is 
scooped  out  and  put  into  boxes,  in  which  it  drains  and 
dries  and  hardens. 

§  117.  Sugar. — The  taste  called  "sweetness"  is  caused 
by  many  different  things.  Some  substances  which  are 
entirely  mineral  are  sweet.  When  a  substance  which  is 
got  from  animals  or  plants  is  sweet,  it  is  called  sugar.  So 
there  is  a  substance  found  in  milk  (see  §  111)  called  milk- 
sugar.  Most  fruits  and  many  vegetables  contain  sugar. 
So  do  the  trunks  of  trees,  such  as  the  maple  and  birch. 
The  sugar  which  is  most  used  is  the  sugar  which  exists  in 
the  sugar-cane  and  the  beet-root.  It  is  called  cane-sugar. 
The  sugar-cane  grows  or  can  grow  in  most  very  warm 
countries.  It  is  a  kind  of  reed,  one  or  two  inches  thick, 
and  from  eight  to  fifteen  feet  high.  When  it  is  ripe,  it 
is  cut  down,  and  the  juice  is  squeezed  out  of  it  by  passing 
it  between  rollers.  The  juice  is  boiled  with  a  little  lime 
(see  §  3).  Then  it  can  be  simply  boiled  down  until  it  is 
so  thick  that,  when  left  to  itself,  it  becomes  partly  solid. 
It  is  then  drained.  The  solid  part  is  brown  sugar  or  moist 
sugar ;  the  part  that  drains  away  is  Tbeacle  or  Molasses. 
The  brown  or  moist  sugar,  when  dissolved  and  filtered 
through  a  filter  made  of  bone-charcoal — that  is,  baked 
bones— becomes  nearly  colourless.  And  this  clear  solution, 
Avhen  the  water  is  driven  off  at  a  low  temperature,  solidifies 
as  white  sugar,  loaf-sugar,  or  sugar-candy.  To  get  the 
water  to  come  off  quickly  at  a  low  temperature,  the  syrup 
is  put  into  a  copper  with  a  tight-fitting  cover,  and  the  air 
is  drawn  out ;  on  warming  the  syrup,  the  water  which  is 


SUGAR,  VINEGAR  109 

with  the  sugar  follows  the  air,  and  leaves  the  solid  sugar 
behind.  Thus  the  sugar  is  dried  without  heating  too 
much,  and  so  without  browning.  Sugar  is  got  from  beet- 
root in  much  the  same  way. 

§  118.  Vinegar. — You  remember  that  when  sugar  or 
starch  ferments,  alcohol  is  formed,  together  with  the  gas 
carbonic  acid.  When  any  liquid  containing  alcohol  and 
vegetable  matter  is  exposed  to  the  air,  the  alcohol  in  it 
unites  with  the  oxygen,  and  so  becomes  sour  or  acid. 
And  the  acid  is  acetic  acid,  and  the  liquid  which  has  thus 
become  acid  is  vinegar.  So  one  can  have  wine-vinegar  or 
beer-vinegar.  If  one  wants  to  make  vinegar  quickly,  the 
beer  or  wine  is  let  trickle  over  shavings,  so  that  it  is 
much  spread  out  to  the  air,  and  so  becomes  quickly 
oxidised  or  changed  to  vinegar.  Acetic  acid  is  also  got 
on  heating  wood  in  a  retort,  as  coal  is  heated  in  gas- 
making.  The  acetic  acid  comes  over  with  the  tar,  and 
has  to  be  cleaned. 

Questions. — How  can  salt  be  got  from  sea-water  ?  How  is  it  that 
masses  of  salt  are  found  in  the  earth  ?  How  is  such  salt  got  clean  ? 
What  substances  are  called  sugars  ?  What  sort  of  plant  is  the 
sugar-cane  ?  How  is  the  sweet  juice  got  from  it  ?  How  is  brown 
or  moist  sugar  got  ?  What  is  treacle  or  molasses  ?  How  is  the 
brown  sugar  made  into  a  white  syrup,  and  how  is  white  sugar  or 
loaf-sugar  got  ?  How  is  acetic  acid  formed  ?  What  is  vinegar  ? 
How  is  vinegar  got  from  beer  and  wine  ?  How  is  acetic  acid  got 
from  wood  ? 


PART    VIII. 

CLEANING. 

XLI. 

Soap,  Soda,   Carbonate  of  Soda,  Washing-soda, 
Hydrochloric  Acid  (Muriatic  Acid). 

Things  to  be  Seen. — Ashes  of  wood — potash— slaked 
lime — talloio  and  other  fats — salt — resin — palm  oil — 
glycerine — linseed  oil — rape  oil — fish  oil — oil  of  vitriol 
— chalk — coal — sawdust — carbonate  of  soda — hydro- 
chloric acid — bicarbonate  of  soda. 

§  119.  Soap. — Soaps  are  made  from  oils  and  fats, 
both  vegetable  and  animal,  by  boiling  them  with  potash- 
lye  or  soda-lye.  Potash-lye  is  made  by  boiling  the  ashes 
of  plants  with  Avater  and  slaked  lime  ;  soda-lye  by  boiling 
washing-soda  (that  is,  carbonate  of  soda,  see  §  120)  with 
water  and  slaked  lime.  Soft  soap,  which  is  sometimes 
used  for  scrubbing  floors  and  for  washing  woollen  cloth,  is 
made  with  potash-lye ;  hard  soap  with  soda-lye.  To 
make  soft  soap,  oils  and  easily  melted  fats  are  used ;  to 
make  hard  soap,  the  less  easily  melted  fats,  such  as 
tallow.  Let  us  suppose  we  want  «a  Hard  Soap.  Some 
washing-soda  is  dissolved  in  water  in  an  iron  pot ;  some 
slaked  lime  is  added,  and  the  whole  boiled  together  and 
allowed  to  settle.  It  is  then  found  that  the  carbonic 
acid  of  the  soda  has  united  with  the  lime,  forming  whit- 
ing, which  settles  down,  and  leaves  the  soda  as  soda-lye. 
This  is  poured  off  from  the  whiting  and  again  boiled,  and 
while  boiling,  tallow  is  added.    After  some  hours'  boiling, 


SOAP,  SODA,  BORAX.  Ill 

the  tallow  is  completely  changed,  its  glycerine  (see  §  44) 
being  dissolved  in  the  water,  and  its  fat-acids  united  with 
the  soda  as  soap.  Some  of  the  soap,  however,  is  dissolved  in 
the  water;  this  is  separated  by  dissolving  common  salt  in 
the  water.  In  the  so-formed  brine  the  soap  is  quite  in- 
soluble. Cast  into  moulds,  dried,  and  cut  into  pieces, 
this  forms  curd-soap.  Such  soap  is  rather  hard,  and  does 
not  lather  well.  To  soften  it  and  make  it  lather,  but 
chieliy  to  make  it  cheaper,  some  resin  is  put  in  with  the 
tallow.  Cocoa-nut  oil  is  often  mixed  with  the  tallow ; 
this  makes  it  softer,  but  such  soap  smells  nasty,  and  is 
half  water.  A  little  palm  oil  improves  yellow  soap. 
Soft  Soap. — The  potash-lye,  made  as  above  described,  is 
boiled  with  animal  or  plant  oils,  such  as  linseed,  rape,  or 
fish  oil.  There  is  this  difference  between  soft  soap  and 
hard  soap — the  soft  soap  contains  the  glycerine  of  the 
fat,  the  hard  soap  does  not.  If  common  salt  be  added 
to  the  lye  with  which  soft  soap  is  being  made,  the  soap  is 
changed  into  soda  soap — that  is,  hard  soap. 

§  120.  Soda,  or  Carbonate  of  Soda,  or  Washing- 
soda,  Borax. — Carbonate  of  soda  is  largely  used  for 
washing,  both  by  itself  and  as  one  of  the  things  used  to 
make  soap  of.  It  is  made  by  pouring  oil  of  vitriol  (sul- 
phuric acid,  see  §  127)  on  common  salt;  this  gives  off  a 
gas  called  Hydrochloric  Acid  Gas,  and  what  is  left  is 
sulphate  of  soda.  The  hydrochloric  acid  gas  is  exceed- 
ingly soluble  in  water,  and  the  water  solution  of  it  is  also 
called  hydrochloric  acid,  or  Muriatic  Acid,  or  Spirit  of 
Salt.  The  sulphate  of  soda  is  mixed  with  chalk  and 
coal,  and  the  three  are  heated  together  in  a  furnace  in 
such  a  way  that  the  flame  can  play  on  them.  When 
cool,  the  mass  so  got  is  heated  with  water,  and  the  clear 
liquid  boiled  to  boil  off  the  water,  while  the  carbonic  acid 
from  burning  coal  sweeps  across  it.  Then  it  is  boiled  to 
dryness,  mixed  with  coal  and  sawdust,  and  again  heated. 
The  part  of  the  mass  so  got  which  is  soluble  in  water  is 
carbonate  of  soda,  and  it  is  got  in  the  form  of  crystals  by 


112  CLEANING   THE   BODY. 

letting  the  hot  solution  cool,  and  by  letting  the  ■water 
pass  off  into  the  air.  Such  crystals  of  carbonate  of  soda 
contain  a  lot  of  water.  If  they  stand  exposed  to  the  air 
they  turn  white;  this  is  because  the  crystals  give  up 
water  to  the  air,  and  at  the  same  time  take  carbonic  acid 
from  the  air,  and  thus  they  change  into  the  powder  called 
Bicarbonate  of  Soda,  which  is  used  for  making  effer- 
vescing drinks,  because  it  contains  more  carbonic  acid 
than  the  crystals.  Bicarbonate  of  soda  is  made  more 
quickly  from  the  carbonate  by  passing  carbonic  acid  gas 
amongst  the  carbonate. 

Cleaning  the  Body. — The  outside  of  the  skin  of  a 
human  being  is  always  dying,  and  wants  to  come  away, 
new  skin  being  formed  beneath  it.  Sweat,  which  is  always 
coming  through  the  skin,  is  not  pure  water,  but  has  in  it 
a  lot  of  salt.  So  that  when  the  water  from  the  sweat  goes 
into  the  air,  the  salt  is  left  behind,  and  the  skin  becomes, 
as  it  were,  pickled  unless  the  salt  is  got  rid  of.  Oil  as  well 
as  sweat  is  always  oozing  through  the  skin.  Dirt  sticks 
to  this  oil.  To  keep  the  skin  in  such  a  state  that  it  does  its 
work  rightly,  it  should  be  rubbed  to  get  rid  of  the  dead  outer 
skin ;  it  should  be  washed  with  water  to  get  rid  of  the 
salt.  If  soap  is  used,  the  oil  is  got  rid  of  more  easily, 
because  soap  contains  plenty  of  soda  to  make  the  skin-oil 
also  into  soap  and  glycerine,  which  mix  with  water.  So 
it  is  good  for  the  sake  of  health  to  rub  the  skin  of  the 
whole  body  with  water  (to  get  rid  of  the  sweat-salt),  soap 
(to  get  rid  of  the  oil),  and  a  rough  towel  (to  get  rid  of 
the  dead  skin).  Unless  this  is  done  about  once  or  twice 
a-week,  the  dead  skin  and  the  oil  rot,  and  the  skin  stinks. 
And  so  it  is  that  people  who  do  not  often  wash  them- 
selves all  over  are  so  nasty. 

Questions. — What  is  soap  made  from  ?  How  is  potash-lye  made  ? 
How  is  soda-lye  made  ?  What  happens  to  tallow  when  it  is  boiled 
with  soda-lye  ?  What  becomes  of  the  glycerine  of  the  soap  ? 
What  is  soap  made  of  ?  How  is  that  part  of  the  soap  which  is  with 
the  glycerine  got  in  the  solid  state  ?  What  is  resin  used  for  in 
soap-making  ?     What  is  soft  soap  ?     How  is  sulphate  of  soda  got  f 


FURNITURE-CLEANING,  HEARTHSTONE,  BATH  DRICK.       11  J 

How  is  hydrochloric  acid  got?  How  is  carbonate  of  soda  got  from 
sulphate  of  soda?  What  happens  to  carbonate  of  soda  when  the 
air  acts  on  it  ?  How  is  bicarbonate  of  soda  made  ?  What  is  always 
happening  to  the  skin  ?  What  is  sweat  made  of?  How  does  the 
salt  of  the  sweat  act  on  the  skin  ?  What  conies  through  the  skin 
besides  sweat  ?  What  is  the  use  of  water  iu  washing  ?  What  of 
soap  ?     What  of  rubbing  with  towels  ? 


XLII. 

Furniture-cleaning,  Hearthstone,  Flanders  Brick, 
Bath  Brick,  Sponge,  Starch,  Prussian  Blue. 

Things  to  be  Seen. — Oil — vinegar- — bees -wax — turpen- 
tine —  hearthstone  —  Bath  brick  —  sponge  — flints  — 
starch — British  gum  (or  dextrine) — Prussian  blue — 
iron — carbonate  of  potash — flour — yellow  prussiate  of 
potash. 

§  121.  Furniture-cleaning. — Deal  tables,  dressers, 
and  all  wood  which  is  not  varnished  or  French-polished, 
and  which  comes  into  contact  with  food,  are  cleaned  by 
simply  scrubbing  them  with  hot  water  and  soap.  But 
soap  destroys  varnish,  and  French  polish,  and  paint, 
because  part  of  the  soda  or  potash  of  the  soap  (see  §  119) 
unites  with  the  resin  of  the  varnish  or  French  polish,  and 
with  the  oil  of  the  paint,  to  make  more  soap.  Spirits 
of  wine  also  attacks  varnishes  and  French  polish.  For' 
paint,  rain-water  and  a  moderately  hard  brush,  for  varnish 
and  French  polish,  a  mixture  of  oil  and  vinegar,  are  the 
most  harmless.  Unvarnished  oak  is  usually  polished 
with  bees'-wax  and  turpentine,  which  does  not  hide  the 
grain  of  the  wood. 

§  122.  Hearthstone. — Hearthstone  is  a  chalky  sand- 
stone, and  is  used  to  whiten  other  stones,  such  as  door- 
steps and  hearths,  by  being  rubbed  over  them  with  water. 

§  123.  Flanders  Brick,  or  Bath  Brick.— The  stuff 

out   of   which   these  are  made  is  found   in   the  mouths 

of  some  rivers  as  a  kind  of  mud  of  fine  sand,  mixed  with 

a  very  little  clay,  just  enough  to  bind  the  grains  of  sand 

u 


114  SPONGE,  STARCH. 

together.  It  is  used  for  cleaning  knives,  fire-irons,  and 
other  iron  articles. 

§  124.  Sponge. — This  substance  is  made  by  animal 
matter  living  in  the  sea,  which  builds  the  sponge  to  live 
in.  It  begins  to  build  upon  almost  any  solid  body  at  the 
bottom  of  the  sea,  especially  in  parts  of  the  Mediter- 
ranean, and  first  forms  a  kind  of  stalk,  which  widens  out 
and  becomes  cup-shaped  as  the  animal  mass  grows.  The 
animal  matter,  which  is  soft  and  transparent,  is  thus 
protected  by  its  house.  The  sponges  are  cut  and 
brought  up  by  divers,  then  squeezed  and  allowed  to 
rot  in  the  sand.  They  are  dried  and  beaten,  to  shake  out 
most  of  the  sand.  Then  they  are  soaked  in  weak 
hydrochloric  acid  (see  §  120),  washed,  and  dried.  The 
raw  •  sponge  is  made  chiefly  of  a  horn-like  substance ; 
it  contains  also  silica  and  carbonate  of  lime.  The  hydro- 
chloric acid  dissolves  out  the  carbonate  of  lime  (which 
makes  the  sponge  harsh  and  stiff),  and  leaves  the  springy 
framework,  made  chiefly  of  horny  stuff  and  silica.  After 
washing  and  drying,  the  sponge  is  ready  for  use.  Sponges 
are  sometimes  bleached,  but  they  are  injured  and  made 
rotten  by  bleaching. 

The  flints  which  are  found  in  chalk  are  silica.  Most 
flints  are  old  sponges  which  have  been  buried  a  long  time 
in  the  chalk  which  has  fallen  upon  them  from  the  sea 
above.  The  original  matter  of  the  sponges  has  for  the 
most  part  been  washed  away,  its  place  being  taken  by 
silica  (see  §§  26,  31). 

§  125.  Starch. — Cuffs,  collars,  shirt-fronts,  and  so  on, 
are  generally  smoothed,  so  that  dust  and  dirt  may  not 
stick  to  them  so  much.  This  is  done  by  starching  them 
before  ironing.  The  starch  used  for  this  is  generally 
made  from  the  potato,  but  much  is  made  from  wheat, 
rice,  or  maize  flour.  The  potatoes  are  thoroughly  washed 
and  scrubbed  clean,  and  then  rasped,  with  water,  into  a 
pulp.  The  pulp  is  stirred  with  more  water,  and  thrown 
.upon  a  fine  sieve  of  wire  or  horse-hair ;  the  water  holding 


STARCn,  BLUE,  PRUSSIAN    BLUE.  115 

the  starch  passes  through  the  sieve  as  a  milky  liquid, 
while  the  libres  are  kept  back.  The  coarser  grains  of 
starch  settle  first,  so  that  if,  after  settling  some  time,  the 
still  milky  liquid  is  poured  into  another  pan,  the  starch 
■which  settles  in  the  second  pan  is  finer  than  in  the  first. 
When  all  the  starch  has  settled  down,  the  clear  liquid  is 
poured  and  drained  from  the  starch,  and  the  starch  is 
allowed  to  dry.  Almost  all  seeds  contain  starch,  and  so 
do  the  other  parts  of  some  plants.  Starch  is  really  made 
of  two  things — little  skins  or  bags,  and  the  stuff  which  is 
in  those  bags  (compare  fat,  §  41).  If  you  pour  boiling 
water  on  starch,  it  swells  and  thickens,  and  when  cold 
forms  a  kind  of  jelly  ;  but  if  you  bake  dry  starch,  or  boil 
it  for  some  time  with  almost  any  weak  acid,  you  turn  it 
into  a  kind  of  gum  called  British  gum,  or  dextrine,  which 
is  very  like  gum-arabic  (see  §  139)  in  its  properties,  but 
smells  nasty.  When  linen  or  calico  has  been  starched, 
and  is  then  ironed  with  a  hot  iron,  some  of  the  starch  is 
changed  into  this  gum,  and  so  the  fibres  and  the  rest  of 
the  starch  are  all  stuck  together,  the  little  holes  in  the 
web  are  filled  up,  and  the  whole  is  smoothed  by  the  iron. 
§  126.  Blue,  Prussian  Blue. — To  correct  the  yellow- 
ness of  old  linen  and  calico,  the  starch  which  is  used  to 
stiffen  them  is  often  slightly  coloured  blue.  The  blue 
used  is  generally  Prussian  Blue.  This  is  a  rather  com- 
plicated body.  It  is  made  as  follows  : — Scraps  of  old 
iron  are  heated  red-hot  in  an  iron  pot,  along  with  car- 
honate  of  potash  and  animal  matter  containing  nitrogen 
— any  animal  matter,  indeed,  except  fat — such  as  horses' 
hoofs,  skins,  &c.  The  mass,  when  cold,  is  boiled  with 
water  and  strained.  Then  yellow  crystals  appear,  on 
cooling.  These  are  what  is  called  yellow  prussiate  of 
potash.  They  contain  iron,  carbon,  potassium,  nitrogen, 
and  a  little  water.  The  solution  of  this  body,  mixed 
with  some  solution  of  iron  in  acids,  gives  the  very  finely 
divided  blue  body  called  Prussian  blue.  And  this  blue 
colour,  mixed  with  white  clay,  is  sold  as  Prussian  blue. 


116  OIL   OF   VITRIOL,  OR   SULPHURIC   ACID. 

Questions. — How  are  deal  tables  and  dressers  cleaned?  How  are 
painted  things  cleaned?  How  are  varnished  and  French-polished 
things  cleaned?  How  is  unvarnished  oak  polished?  What  is 
hearthstone,  and  how  and  for  what  is  it  used  ?  What  is  Flanders 
or  Bath  brick  ?  What  is  it  used  for  ?  Where  are  sponges  found  ? 
What  sort  of  animal  is  the  sponge  animal  ?  How  is  the  sponge 
cleaned  ?  How  is  it  softened  ?  What  is  the  sponge,  as  sold  in 
shops,  made  of?  How  have  flints  been  made?  How  is  starch 
made  ?  How  is  fine  starch  freed  from  coarse  starch  ?  What 
happens  if  you  pour  boiling  water  on  starch  ?  How  is  British  gum 
or  dextrine  made?  What  happens  when  starched  clothes  are 
ironed  ?  How  is  yellow  prussiate  of  potash  made  ?  How  is 
Prussian  blue  made  ? 


XLIII. 

Oil  of  Vitriol,  Nitric  Acid,  Pumice-stone,  Cleaning 
Silver  and  Iron,  Emery,  Chloride  of  Lime. 

Things  to  be  Seen. — Sulphur — burning  sulphur — nitre 
— nitric  acid — drawing  of  making  sulphuric  acid — 
sulphuric  acid  — pumice-stone — whiting  —  spirits  of 
wine — rouge — emery  —  Tripoli-powder — rotten-stone — 
bleaching-powder. 

§  127.  Oil  of  Vitriol,  or  Sulphuric  Acid.— This, 

wlien  very  much  diluted  with  water,  is  often  used  to  clean 
brass  plates.  It  is  made  by  burning  sulphur  in  the  air, 
and  then  mixing  the  burnt  or  oxidised  sulphur,  which  is 
a  gas,  with  water,  vapour,  and  more  air,  and  another  gas 
made  of  nitrogen  and  oxygen.  This  last-named  gas  is 
got  from  nitric  acid  (see  page  117),  and  has  the  power  of 
giving  up  some  of  its  oxygen  to  the  burnt  sulphur,  and  so 
burning  it  further.  The  gas  which  has  lost  uxygen  gets 
it  again  from  the  air,  and  again  gives  it  to  more  of  the 
burnt  sulphur,  and  so  on.  The  sulphur  which  is  thus 
thoroughly  oxidised  or  burnt  forms,  with  the  water, 
sulphuric  acid.  Most  of  the  water  can  be  boiled  away, 
and  what  is  left  is  oil  of  vitriol,  a  dangerous  stuff  to 
handle,  because  it  eats  away  most  things  it  touches. 


NITRIO    ACID,  PUMICE-STONE,  CLEANING    SILVER.       117 

Nitric  Acid,  called  also  Aqua-fortis,  which  is  Latin 
for  strong  water,  is  got  by  pouring  oil  of  vitriol — that  is, 
sulphuric  acid — upon  nitre — that  is,  saltpetre  (also  called 
nitrate  of  potash) — or  upon  nitrate  of  soda  (see  §  50).  If 
these  things  are  heated  together  there  is  formed  sulphate  of 
potash  (or  soda),  Avhile  the  nitric  acid  boils  away,  and 
can  be  caught  by  cooling. 

So  sulphuric  acid  is  made  by  using  nitric  acid,  and 
nitric  acid  by  using  sulphuric  acid.  How  can  this  be? 
Because  a  little  nitric  acid  changes  a  great  deal  of  partly 
burnt  sulphur  into  fully  burnt  sulphur,  aided  by  the 
moist  oxygen  of  the  air.  In  fact  we  may  liken  nitric 
acid,  as  far  as  it  is  concerned  in  the  making  of  sulphuric 
acid,  to  yeast  in  the  fermentation  of  dough  or  Avort  (see 
§§107,  i  15). 

§  128.  Pumice-stone. — Pumice-stone  is  used  for  rub- 
bing off  the  surfaces  of  things,  and  so  for  cleaning  them. 
It  is  a  stone  full  of  holes,  and  therefore  light.  A  lump  of 
it  will  float  in  water,  but  the  powder  of  it  sinks,  because 
the  grains  of  the  powder  are  not  full  of  holes.  It  is  thrown 
out  of  volcanoes,  having  been  melted ;  and  the  holes  in  it 
are  made  by  swelling  gases,  like  the  hollows  in  asrated 
bread  (see  §  10S).  Pumice-stone  is  useful  to  rub  off  old 
paint  from  wood,  and  for  rubbing  stains  off  the  lingers. 

§  129.  Cleaning  Silver  and  Silver  Plate. — Whiting 
is  made  into  a  paste  with  spirit  of  wine,  and  the  silver 
surface  is  covered  with  this.  When  the  paste  is  dry,  it 
is  brushed  off  with  a  soft  brush,  and  the  surface  is  rubbed 
with  wash-leather.  Pouge — that  is,  very  fine  iron-rust — 
is  often  used  in  the  same  way. 

§  130.  Cleaning  Iron  and  Steel. — Iron  and  steel 
things  are  ■  cleaned  and  polished  by  being  rubbed  with 
line  Emery  or  Eotten-stone,  or  Tripoli-powder,  with 
an  oily  rag.  Eotten-stone  is  very  tine  emery,  and  so  is 
Tripoli-powder.  All  three  are  nearly  pure  alumina 
(oxide  of  aluminum)  ;  and  though  a  lump  of  rotten-stone 
can  be  easily  broken,   the  little  grains  of  Avhich  it  is 


118       CLEANING  IRON  AND  STEEL,  CHLORIDE  OP  LIME. 

formed  are  very  hard  indeed.  Lumps  of  emery  are 
broken  by  the  hammer,  and  crushed  to  powder  by  a  beam 
shod  Avith  iron,  which  rises  and  falls  upon  the  emery. 
The  powder  is  sifted  through  sieves  of  different  degrees 
of  fineness.  But  for  some  purposes  even  the  finest  sieves 
would  be  too  coarse,  and  let  grains  too  large  fall  through. 
The  finest  emery  powder  got  by  sifting  is  stirred  up  in  a 
vat  with  water ;  the  larger  grains  fall  first.  After  wait- 
ing some  time,  the  unsettled  liquid  is  run  into  another 
vat,  some  more  settles,  which  is  liner  than  the  first ;  then 
the  liquid  is  run  into  a  third  vat,  and  part  allowed  to 
settle,  and  so  on.  The  finest  emery  is  found  at  the 
bottom  of  the  last  vat,  and  the  water  above  it  is  clear. 
Sand-paper  and  glass-paper  are  made  simply  by  strewing 
sand  or  powdered  glass  on  paper  wetted  with  glue. 

§  13.1.  Chloride  of  Lime  (Bleaching-powder). — 
Chlorine  is  an  element.  It  is  a  gas  got  by  warming 
hydrochloric  acid  (see  §  120)  with  oxide  of  manganese — 
a  mineral  found  in  Cornwall  and  elsewhere.  When  you 
let  chlorine  come  amongst  slaked  lime,  the  chlorine  is 
absorbed,  and  the  oxygen  loosened.  Chloride  of  lime 
is  made  by  passing  chlorine  amongst  lime.  The  oxygen, 
so  apt  to  escape,  burns  things.  Amongst  other  things 
which  the  oxygen  burns  are  the  seeds  of  plants  and 
animals ;  so  that  chloride  of  lime  is  death  to  feeble  or 
small  living  things.  Thus  it  is  used  to  disinfect — that  is, 
to  kill  living  things,  such  as  the  fever-germs.  I  do  not 
think  it  is  yet  known  whether  these  germs  are  animal  or 
vegetable. 

Questions. — What  is  oil  of  vitriol  made  of?  What  is  it  used  for 
in  cleaning  ?  How  is  nitric  acid  got  ?  What  is  got  when  sulphur 
burns  in  the  air  ?  How  is  sulphuric  acid  (oil  of  vitriol)  made  ? 
Where  is  pumice-stone  found  ?  Why  do  lumps  of  it  float,  while, 
when  powdered,  it  sinks?  What  is  it  used  for?  How  is  silver  or 
silver  plate  cleaned?  what  is  rouge?  What  are  iron  and  steel 
cleaned  with  ?  What  are  rotten-stone,  Tripoli-powder,  and  emery- 
made  of  ?  How  is  emery  powder  got  of  different  finenesses  ?  How 
is  chloride  of  lime  used?  How  does  chloride  of  lime  kill  fever 
germs  ? 


PART    IX. 

WHITING  AND  TPJNTING. 

XLIV. 

Writing,  Pens,  Ink,  Green  Vitriol,  Sulphate  of 
Iron,  Red  Ink,  Blue  Ink,  Oxalic  Acid. 

Things  to  be  Seen. — Quills  and  quill  pens — steel  rib- 
bon— sulphuric  acid — gall-nuts — sulphate  of  iron — 
Brazil  wood — Prussian  blue — oxalic  acid. 
§  132.  Writing. — Paper-making  has  been  described  in 
§§  57,  58.  Pens  are  usually  either  quills  or  steel.  The 
quills  are  generally  the  longest  feathers  from  the  wings  of 
geese.  The  quill  ends  of  such  feathers  are  thrust  for  two 
or  three  seconds  into  hot  tine  sand  or  into  an  oven. 
They  are  then  scraped  with  a  blunt  knife,  and  rubbed 
with  flannel  or  dry  fish-skin.  Steel  Pens  are  made 
from  ribbons  of  the  best  steel  (see  §  80).  The  ribbons 
are  cleaned  with  dilute  sulphuric  acid  (see  §  127),  and 
rolled  between  steel  rollers  till  they  have  the  proper 
thickness.  Then,  by  means  of  a  "  punch,"  a  piece  is  cut 
out,  of  the  shape  which  the  pen  we  see  would  have  if  it 
were  flattened  out,  except  that  the  end  is  square,  does  not 
taper  to  a  point,  and  is  not  slit.  Next,  the  hole  is  punched 
out  which  you  see  at  the  top  of  the  slit.  The  pieces  are 
next  heated,  and  allowed  to  cool  slowly,  whereby  they  are 
softened.  .Next  they  are  bent  round,  so  as  to  be  hollow 
on  one  face.  At  this  stage  tbey  are  hardened,  which  is 
done  by  heating  them  red-hot  in  an  iron  box,  so  that  they 
shall  not  rust,   and  throwing  them  into  oil  (see  §  80). 


120  PENS,  INK. 

After  they  have  been  cleaned  from  the  oil,  they  are  tem- 
pered by  heating  them  to  a  certain  hotness  below  redness 
(see  §  81),  and  letting  them  cool.  Rubbing  with  sand 
polishes  them.  Next  the  nib  is  made — that  is,  the  steel 
is  pointed.  This  is  done  by  grinding  on  a  wheel  made  of 
emery  powder  (see  §  130)  and  clay  baked  together  (in  the 
form  of  a  wheel)  into  a  sort  of  emery  brick.  The  pen  is 
now  laid  upon  a  chisel  standing  upright,  so  that  the  edge 
of  the  chisel  reaches  from  the  point  of  the  pen  to  the  hole 
in  it.  Another  such  chisel  is  forced  down,  and  the  steel 
is  split  from  nib  to  hole.  The  two  chisel  edges  meet  one 
another  in  the  same  way  that  the  two  blades  of  a  pair  of 
scissors  do  This  forms  the  slit.  Next  comes  the  final 
tempering,  and  lastly  the  lacquering  (see  §  69). 

§  133.  Ink. — In  §  97  you  saw  how  tannin  (a  stuff 
which  exists  in  the  bark  of  the  oak)  is  used  for  tanning 
skins,  and  so  making  leather.  There  is  an  insect  which 
makes  a  little  hole  in  the  skin  or  bark  of  the  leaves  and 
stalks  of  the  growing  oak,  and  lays  an  egg  there.  Part  of 
the  juice  of  the  leaf  which  otherwise  would  form  outer 
wood  and  inner  bark  (see  §  34)  collects  and  hardens  into 
little  balls  round  the  egg,  forming  a  sort  of  cocoon  (see 
§  88).  But  the  nature  of  the  juice  is  somewhat  changed 
in  hardening,  and,  instead  of  containing  only  tannin, 
these  oak-galls,  or  Gall-nuts,  as  they  are  called,  contain 
small  quantities  of  a  body  called  gallic  acid  as  well.  The 
nut-galls  used  for  making  ink  are  imported  chiefly  from 
Turkey,  and  the  insect  which  causes  them  is  a  kind 
of  wasp.  Such  galls  are  broken  up  and  boiled  with 
water.  To  this,  when  strained  from  the  insoluble  stuff, 
some  dissolved  gum  is  added,  and  then  some  dissolved 
Copperas  (Gkeen  Vitriol,  Sulphate  of  Ikon).  The 
whole  turns  nearly  black,  and  this  is  ink.  It  turns 
si  ill  blacker  when  it  is  exposed  to  the  air,  from  which  it 
absorbs  oxygen,  so  that  ink-writing  darkens  by  time. 
'Che  gum  merely  makes  the  ink  smoother,  and  helps  to 
stick  it  to  the  paper.     The  tannin  in  the  ink  also  forms  a 


KED    INK,  BLUE    INK.  121 

kind  of  leather  with  the  glue  with  which  the  paper  has 
heen  sized  (see  §§  25,  57). 

§  134.  Red  Ink  is  usually  made  by  hoiling  the  wood  of 
a  tree  (called  Brazil  wood),  in  the  form  of  shavings  or 
sawdust,  with  water  for  a  long  time.  The  liquid  is 
poured  from  the  insoluhle  parts,  and  some  gum  is  added. 

§  135.  Blue  Ink. — Prussian  blue  (see  §  126)  dissolves 
in  Oxalic  Acid.  Oxalic  acid,  which  is  a  deadly  poison, 
exists  in  small  quantities  in  sorrel  in  union  with 
potash,  as  salts  of  sorrel.  Oxalic  acid  can  be  made 
artificially  in  many  ways.  If  a  mixture  of  very  strong 
potash  and  soda  lyes  (see  §  119)  is  mixed  into  a  sort  of 
paste  with  sawdust,  and  heated,  oxalate  of  soda  is  formed, 
and  this,  when  dissolved,  gives  up  its  oxalic  acid  to 
slaked  limej^and  oxalate  of  lime  is  formed,  Avhich,  being 
insoluble  in  water,  may  be  washed  clean.  This  body  is, 
in  its  turn,  mixed  with  sulphuric  acid  (see  §  127),  where- 
upon sulphate  of  lime  (see  §  12)  is  formed.  This  gypsum, 
being  insoluble,  can  be  separated  by  straining,  and  the 
liquid  which  comes  through  contains  the  oxalic  acid. 
Most  of  the  water  is  driven  off  by  heat,  and  the  acid,  on 
cooling,  forms  crystals  containing  water.  Blue  ink  is 
made  by  dissolving  Prussian  blue  in  oxalic  acid. 

Various  inks  are  made  from  coal-tar,  but  they  are  not 
very  useful  for  handwriting. 

Questions. — What  quills  are  used  for  pens  ?  What  is  done  to  the 
quills  so  as  to  make  them  ready  for  pens?  How  is  steel  ribbon 
cleaned  and  cut  into  pieces  for  pens  ?  How  is  the  hole  made  ?  How 
are  the  pieces  no"w  softened  ?  After  bending,  how  are  the  pieces 
hardened  ?  How  are  they  tempered  ?  How  are  they  polished  ? 
How  are  they  pointed?  How  is  the  slit  made?  How  are  they 
finished  ?  How  and  where  are  gall-nuts  formed  ?  How  are  gall- 
nuts  used  in  making  ink  ?  What  is  copperas  or  green  vitriol  ? 
What  happens  when  dissolved  green  vitriol  and  water  in  which 
gall-nuts  have  been  boiled  are  mixed  ?  What  is  red  ink  ?  Where 
is  oxalic  acid  found  in  nature  ?  What  is  made  by  heating  potash 
and  soda  lye  with  sawdust  ?  What  is  formed  by  mixing  oxalate  of 
soda  with  slaked  lime  ?  What  is  formed  when  oxalate  of  lime  is 
mixed  with  sulphuric  acid  ?     How  is  blue  ink  made  ? 


122  BLACK-LEAD,  INDIA-RUBBER. 


XLV. 

Black-lead,  Graphite,  India-rubber,  Sealing-wax, 
Gum-arabic,  British  Gum,  Dextrine. 

Things  to  be  Seen. — Black  lead — india-rubber — shell- 
lac — rosin — turpentine — vermilion — lamp-black — gum- 
arabic — dextrine. 
§  136.  Black-lead  —  Plumbago,  Graphite. — This 
substance,  when  pure,  is  nothing  but  the  element  carbon. 
It  is  found  in  nature,  and  sometimes  in  small  quantities 
in  a  state  pure  enough  to  be  used  for  writing.  It  has 
then  only  to  be  cut  by  fine  saws  into  square  strips,  and 
put  into  grooves  in  the  flat  sides  of  wooden  rods,  and 
covered  with  other  wooden  strips  glued  on  the  top. 
Impure  plumbago  is  made  pure  by  grinding  it  to  a  fine 
powder,  and  dissolving  out  the  impurities  with  sulphuric 
and  other  acids.  It  is  then  made  ready  for  pencils  by 
mixing  the  powder  with  clay,  and  baking  the  two  together. 
Pencils  of  different  degrees  of  hardness  can  thus  be  made; 
for  the  higher  the  temperature  and  the  more  the  clay,  the 
harder  is  the  pencil.  To  avoid  loss  by  sawing,  the  paste 
of  clay  and  plumbago  is  pressed  into  moulds,  and  then 
baked.  The  black  lead  of  most  pencils,  except  those 
which  are  wanted  very  soft,  is  heated  and  plunged  into 
tallow  or  paraffin.  This  makes  it  rather  harder,  but 
smoother  to  write  with. 

§  137.  India-rubber — Caoutchouc. — For  rubbing  out 
marks  on  paper  made  by  black-lead  pencils,  either  bread- 
crumbs or  india-rubber  is  generally  used.  The  two 
substances  act  in  the  same  way.  Little  pieces  of  the 
bread  or  india-rubber  are  rolled  off  and  pressed  upon  the 
black-lead  marks.  The  black-lead  sticks  to  them,  and  is 
torn  off  from  the  surface  of  the  paper.  If  you  steam  the 
paper  on  which  the  plumbago  marks  are,  you  soften  the 
size  on  the  surface  (see  §§  25,  57),  and  the  plumbago  dust 
sinks  into  this.     When  dry  again,  you  cannot  rub  the 


INDIA-RUBBER,  SEALING-WAX.  123 

marks  out  in  the  same  way,  because  the  plumbago  is  now 
embedded.      The  writing  is  "  fixed." 

Caoutchouc  or  india-rubber  is  produced  by  trees  grow- 
ing in  Brazil,  East  India,  Java,  West  Africa,  and  other 
hot  countries.  Holes  are  bored  in  the  roots,  trunks,  and 
branches  of  these  trees,  and  tubes  or  little  gutters  are  put 
in.  A  milky  juice  runs  out,  and  is  caught  in  pots  tied  at 
the  proper  places.  A  lump  of  dry  clay,  shaped  like  a 
pear,  and  having  a  handle,  is  dipped  into  the  juice,  and 
then  held  over  a  fire.  This  drives  off  the  water,  and 
leaves  the  caoutchouc  as  a  skin  sticking  to  the  clay.  It 
is  again  dipped,  and  dried  a  great  many  times.  One  coat 
sticks  to  the  other,  till  the  caoutchouc  is  an  inch  or  two 
in  thickness.  Then  the  clay  is  broken  out,  and  the 
caoutchouc  is  left  in  the  form  of  bottles,  and  is  called 
bottle  india-rubber.  The  juice  is  often  simply  allowed  to 
dry  in  cakes.  Such  india-rubber  often  contains  dirt,  and 
it  is  not  alike  all  through.  It  is  therefore  torn  to  pieces 
and  worked  with  water,  by  being  put  with  water  in  a 
round  box,  in  whose  inside  spikes  are  fixed,  all  pointing 
inwards,  but  leaning  one  way,  as  though  they  had  all 
been  bent  by  a  sweep  of  the  hand.  Inside  this  box  is  a 
wheel  having  spikes  pointing  outwards,  and  nearly 
touching  the  fixed  spikes  point  to  point ;  the  spikes  on 
the  wheel  are  all  bent  the  other  way  to  those  on  the  box. 
The  crude  india-rubber  being  put  in  with  water,  the 
inner  wheel  is  turned  round,  and  the  caoutchouc  is  torn  to 
pieces.  It  gets  hot  and  soft  like  dough,  so  that  it  is 
thus  thoroughly  mixed  and  washed. 

§  138.  Sealing-wax. — JSealing-wax  is  made  by  melting 
together  rosin  (see  §  67),  shell-lac  (see  §  68),  and  a  little 
oil  of  turpentine  (see  §  67);  the  turpentine  called  Venice 
turpentine  gives  the  best  wax.  The  red  colour  of  the 
common  sealing-wax  is  got  by  mixing  with  the  above 
some  vermilion  in  powder.  Vermilion  is  a  red  body  got 
by  uniting  sulphur  (see  §  49)  with  mercury  (see  §  22). 
Black  wax  is  made  by  mixing  lamp-black  (a  fine  form  of 


124  GUM-ARABIC,  BRITISH    GUM,  TYPE. 

soot,  and  which  is  nearly  pure  carbon — see  §  32)  with  the 
rosin,  shell-lac,  and  turpentine.  The  shell-lac  by  itself  is 
rather  too  hard  to  melt.  The  rosin  is  cheap,  and  the 
mixture  of  these  two  melts  more  easily  than  the  shell-lac 
alone ;  but  it  is  too  brittle.  The  turpentine  makes  the 
mixture  of  the  two  rosins  softer  and  tougher. 

§  139.  Gum-arabic. — The  juice  of  various  kinds  of 
acacia  trees  which  grow  in  Upper  Egypt,  West  Africa, 
India,  and  Arabia  oozes  out  of  the  tree,  and  hardens  in 
the  air.  It  is  soluble  in  water,  and  is  used  for  gumming 
envelopes. 

§  140.  British  Gum,  or  Dextrine. — British  gum,  or 
dextrine,  is  made  from  starch,  either  by  heating  it  by 
itself  in  a  stove  a  good  deal  hotter  than  boiling  water,  but 
not  hot  enough  to  scorch  it,  or  by  mixing  the  starch  with 
water  and  a  very  little  nitric  acid  (see  §  127),  and  allowing 
it  to  dry.  After  this  it  is  heated  as  hot  as  boiling  water. 
Dextrine  is  cheaper  than  gum-arabic,  but  it  has  a  nasty 
smell. 

Questions. — What  is  pure  black-lead  ?  How  is  black-lead  cleaned  ? 
How  is  it  made  as  hard  as  it  is  wanted  ?  How  is  it  made  into 
sticks  for  pencils  ?  How  do  india-rubber  and  bread  crumbs  act  in 
rubbing  out  black-lead  marks  on  paper  ?  How  can  pencil  marks 
be  lixed  on  paper  ?  Where  do  india-rubber  trees  grow  ?  How  is 
their  juice'  got  ?  How  is  the  juice  dried  and  hardened  ?  How  is  the 
india-rubber  cleaned?  What  is  sealing-wax  made  with  ?  How  is 
it  made  red  ?  What  is  vermilion  ?  How  is  black  wax  made  ? 
What  is  the  use  of  the  rosin,  and  what  of  the  turpentine  in  sealing- 
wax  ?    What  is  gum-arabic  ?    H  ow  is  British  gum  or  dextrine  made  ? 


XLVI. 

Printing,  Type,  Antimony,  Printers'  Ink. 
Things  to   be    Seen. — Specimens   of  type — lead — anti- 
mony— rosin — linseed  oil — yellow  soap — lamj)-black — 
glue  dissolved  in  treacle  and  allowed  to  set. 

§  141.  Type. — A  left-handed  drawing  of  a  'letter  is 
scratched  by  a  hard  steel  point  on  a  soft  steel  plate  thus, 
[ffl].      The  dotted  outline  shows  the  edge  of  the  plate, 


TYTE,   PRINTERS'  INK.  125 

The  metal  is  cut  away  from  around  the  letter,  leaving  it 
standing  out  i'flj.  The  whole  is  now  hardened  (see  §  80), 
and  being  turned  over,  is  driven  by  a  blow  a  little  way  into 
a  thickish  sheet  of  brass.  A  hole  or  mould  js  thus  made 
in  the  brass,  which  is  right-handed,  thus,  |^j.  The  plate 
of  brass,  thus  stamped,  is  made  to  form  the  bottom  of  a 
little  steel  box  with  movable  sides.  Into  this  box  is 
poured  a  melted  mixture  (alloy)  of  lead  (see  §§  15,  17) 
and  Antimony  (see  §  75),  to  which  a  little  tin  (see 
§  21)  is  sometimes  added.  An  upward  jerk  sends 
the  metal  well  down  into  the  mould,  and  hardens 
the  face  of  the  type.  The  antimony  makes  the  lead 
hard ;  and  it  has  the  rare  property,  which  it  gives  to  the 
alloy,  of  getting  a  little  bigger  as  it  becomes  solid.  The 
alloy  thereby  forces  itself  thoroughly  into  the  sharp  edges 
of  the  mould.  When  solid,  the  casting  is  taken  out, 
its  bottom  levelled  and  its  sides  polished,  and  it  is 
made,  from  the  face  of  the  letter  to  the  bottom,  exactly 
of  a  certain  length.  It  is  now  a  type-letter,  and  is  of 
course  left-handed,  fl  .  Any  number  of  types  can  be  cast 
from  the  same  mould.  If  the  same  is  done  with  the  other 
letters  of  the  alphabet,  and  with  the  numerals,  0,  1,  2,  3, 
4,  5,  6,  7,  8,  9,  stops,  CAPITALS,  italics,  and  so  on,  we  get 
what  is  called  a  fount  of  type.  Types  are  now  almost 
always  cast  by  the  aid  of  machinery. 

To  print,  the  letters  are  set  up  side  by  side  in  a  small 
frame  (called  a  "stick")  held  by  the  compositor,  who 
begins  to  arrange  the  type  in  the  left-hand  corner  of 
the  frame,  ra  IHI2  M.V7L.  When  these  letters  "are  inked, 
turned  over,  and  pressed  on  paper,  the  printing  appears 
in  this  way.  When  the  setting  of  the  type  is  completed, 
it  is  wedged  up  in  an  iron  frame,  laid  on  the  press,  and 
prepared  for  printing. 

§  142.  Printers'  Ink. — Printers'  ink  is  made  by  dis- 
solving rosin  (see  §  67)  in  hot  linseed  oil  (see  §  59) 
which  has  been  boiled  until  it  takes  fire  when  a  light  is 
put  to   it.       To  this  mixture  is  added  lamp-black  (see 


126  PRINTING. 

§  32),  and  sometimes  yellow  soap  (see  §  119)  and  Prussian 
blue  (see  §  126).  The  whole  is  then  ground  together 
between  iron  or  hard  stone  rollers  till  it  gets  quite  fine  and 
smooth. 

The  frame  (or  "  forme  ")  of  type  is  inked  by  rolling  its 
surface  with  an  elastic  roller  covered  with  the  ink.  The 
roller  is  generally  made  of  a  mixture  of  strong  glue  (see  § 
25)  and  treacle  (see  §  117).  The  liquid  glue  sets  to  a  very 
firm  jelly,  and  the  treacle  prevents  the  jelly  drying  up. 
The  paper,  which  is  slightly  damped,  is  pressed  upon  the 
t}rpe,  and  becomes  thus  inked  by  the  type,  or  printed. 
These  are  the  chief  things  about  "  hand  "  printing. 

Questions. — How  is  the  punch  made  for  making  type  ?  How  ia 
the  type-mould  made  by  means  of  this  punch  ?  What  is  type- 
metal  made  of  ?  What  is  the  use  of  the  antimony  ?  What  is  a 
fount  of  type  ?  How  is  the  type  set  up  by  the  compositor  ?  What 
is  printers'  ink  made  of,  and  how  is  it  made  ?  How  is  the  type 
inked  f    What  is  the  printer's  inking  roller  made  of  ? 


INDEX. 


The  numbers  refer  to  the  2)aragraphs  (marked  §). 


Acetic  Acid,  118. 
Air-gas  burners,  32. 
JSrated  bread,  108. 
Air,  30  ;  air-gas  burner,  32. 
Alcohol,  115. 
Alpaca,  95. 
Ammonia,  40. 
Animal  oils,  47. 
Antimony,  75,  141. 
Aqua-fortis,  127. 
Arabic,  gum,  139. 
Ashes,  2. 
Atmosphere,  30. 
Balk  of  timber,  35. 
Barm,  107. 
Bast,  104. 
Bath  brick,  123. 
Battens,  37. 
Beer,  115. 
Beet-root,  117. 
Bicarbonate  of  soda,  120. 
Biscuits,  109. 
Blacking,  100. 
Blankets,  70. 
Bleaching-powder,  131. 
Blue,  Prussian,  62,  126. 
Bolting,  106. 
'  Bone-charcoal,  117;  bone-ash,50. 
TCorax.  83. 
Bran,  106. 
Brass,  20. 

Bread,  106  ;  aerated,  108. 
Breeze,  2 
Brimstone,  49. 
Bricks,  5. 
Britannia  metal,  75. 


Broom,  the,  104  ;  brooms,  104. 

Brushes,  104. 

Butter,  113. 

Calf-skin,  97. 

Calico,  54. 

Candles,  41-45. 

Cane  chairs,  63. 

Canvas,  55. 

Caoutchouc,  102,  137. 

Carbon,  30. 

Carbonate  of  soda,  120. 

Carbonic  acid,  3,  8,  30-32, 107. 

Carpets,  71. 

Casein,  114. 

Cast  iron,  16. 

Chaff,  106. 

Chalk,  26. 

Charcoal,  30,  38. 

Chamois,  99. 

Cheese,  114. 

Chimney  pots,  6. 

China-clay,  84. 

Chlorate  of  potash,  51. 

Chloride  of  lime,  131. 

Chlorine,  131. 

Chrome  yellow,  62. 

Cinders,  2. 

Cinnabar,  22. 

Clamp,  brick,  5. 

Clay,  5  ;  China,  84. 

Cleaning,   furniture,   121  ;   iron, 

130;   silver,  129;  steel,  130; 

the  skin,  120. 
Cloth,  broad,  86  ;  woollen,  86. 
Coal,  seams  of,  1 ;  coal-gas,  40. 
Cocoa-nut,  oil,  48  ;  fibre,  72. 


128 


INDEX. 


Cocoon,  88. 

Coke,  2. 

Colours,  paint,  59  ;  wall-papers, 

Colza  oil,  48.  [62. 

Combs,  102. 

Composite,  44. 

Concrete,  3. 

Copal,  gum,  67. 

Copper,  15,  19. 

Copperas,  133. 

Cornish  clay,  84. 

Cotton,  54;  thread,  54  ;  wool,  54. 

Crape,  94. 

Cream,  112;  of  tartar,  103. 

Crockery,  84. 

Crystal  «lass,  27. 

Curds,  114. 

Currying,  97. 

Deals,  36,  37. 

Dew,  33. 

Dextrine,  107,  140. 

Dips,  41. 

Distilled  water,  33. 

Dough,  107. 

Drain-pipes,  6. 

Draw-plate,  103. 

Earthenware,  84. 

Ebonite,  102;  ebony,  36. 

Electro-plate,  79. 

Elements,  29. 

Emery,  130. 

Enamel,  83. 

Esparto,  57,  58. 

Fat,  41. 

Felspar,  85. 

Felt,  87. 

Fermentation,  107,  115. 

Fever-germs,  131. 

Fire,  3 1  ;  fire  damp,  40. 

Flail,  106. 

Flame,  32. 

Flanders  brick,  123. 

Flax,  55. 

Flint,  3 ;  flints,  124. 

Floss  silk,  88. 

French  polish,  68. 


Friction,  53. 

Fuller's  earth,  86;  thistle,  86. 

Fulling,  86. 

Fur,  101. 

Furniture-cleaning,  121. 

Fustian,  92. 

Gall  nuts,  133. 

Galvanised  iron,  24. 

Gas,  coal,  40. 

Gelatine,  97. 

German  silver,  74. 

Germination,  115. 

Germs,  fever,  131. 

Glass,  27. 

Glaze,  6,  85. 

Glucose,  107. 

Glue,  25. 

Gluten,  106. 

Glycerine,  44. 

Grains,  115. 

Granite,  11. 

Graphite,  136. 

Green  wall-papers,  62. 

Gum,  Arabic,  139;  British,  140  J 
copal,  67 ;  Sandarach,  68. 

Gypsum,  12. 

Hail,  33. 

Hearthstone,  122. 

Hemp,  56. 

Hoar-frost,  33. 

Hops,  115. 

Horse-hair,  66. 

Hydrochloric  acid,  120. 

Hydrogen,  33. 

Ice,  33. 

India-rubber,  102,  137. 

Ink,  133;  blue,  135;  red,  134; 
printers',  142. 

Iron,  15;  furnace,  16;  galva- 
nised, 24;  cleaning,  130. 

Kerseymere,  93. 

Kid,  leather,  98. 

Kiln,  lime,  3  ;  brick,  5. 

Lacquer,  69. 

Lamp-black,  32,  142. 

Lard,  101. 


IXDKX, 


129 


Laths,  37. 

Lead,  15,  17;  white,  59;  black, 

Leaf-wood,  3(5.  ."[lob. 

Leather,  97. 

Leaven.  107. 

Lime,  slaked,  3  ;  chloride  of,  131 ; 

quick-lime,  3  ;  limestone,  3,  8. 
Linen,  55. 
Linseed  oil,  59. 
Litharge,  59. 
Looking-glasses,  73. 
Lye,  potash,  119;  soda,  119. 
Magnesia,  67. 
Malt,  115;  malt-kiln,  115. 
Marble,  3,  9. 
Marsh-gas,  40. 
Matches,     49-52  ;     safety,     53 ; 

lighting  of,  53. 
Mash,  115. 
Mats,  72. 

Matter,  what  it  is  made  of,  29. 
Mercury,  22. 
Merino,  93. 
Metals  in  general,  15. 
Milk,  111  ;  milk-sugar,  111. 
Molasses,  117. 
Mortar,  4. 
Muriatic  acid,  120. 
Muslin,  54. 
Nap  on  cloth,  86. 
Needles,  105. 
Nickel.  74. 
Nitre,  50. 

Nitrate  of  potash,  50;  of  soda,  50. 
Nitric  acid,  127. 
Nitrogen,  30. 

Oatmeal,  110;  porridge,  110. 
Oil-clotli,  61. 
Oil,   linseed,   59  ;   of  turpentine, 

36,  67  ;  of  vitriol,  127  ;  olive, 

&c,  48;  paraffin,  45;  porpoise, 

47. 
Osiers,  65. 
Oxalic  acid,  135. 
Oxidation,  31    32. 
Oxygen,  30,  33. 


Paints,  59. 

Paper,  57,  58. 

Paraffin,  solid,  45;  oil,  46. 

Peat,  39. 

Pens,  132. 

Petroleum,  46. 

1'ewter,  82. 

Pine-wood,  36. 

Pins,  103. 

Pith,  34. 

Phosphorus,  phosphoric  acid,  50. 

Planks,  37. 

Plaster  of  Paris,  12. 

Plate,  glass,  27 ;  silver,  77. 

Plumbago,  136. 

Polish,  French,  68. 

Porcelain,  85. 

Porridge,  oatmeal,  110. 

Potash,  lye,  119  ;  chlorate  of,  51. 

Pottery,  84. 

Printers' ink,  142;  printing,  141. 

Prussian  blue,  126. 

Pumice-stone,  128. 

Putty,  28. 

Quioksilveu,  22. 

Rennet,  114. 

Resin  or  rosin,  67. 

Rotten-stone,  130. 

Pouge,  129. 

Rushes,  64. 

Rusting,  31. 

Sal-amm  iniac,  24. 

Saltpetre,  50. 

Salt,  table,  116;  spirit  of,  120. 

Sand,  sea,  3 ;  river,  4  ;  saadstoce, 

10. 
Satin,  89. 
Sealing-wax,  138. 
Seal  oil,  47. 
Serge,  93. 
Shamoy,  99. 
Shell-lac,  68. 
Shingles,  14. 
Shuttle,  54. 
Silica,  31. 
Silk,  88. 


130 


INDEX. 


Silver,  76 ;  German,  74  ;  plate, 
77;  cleaning,  129;  silvering, 
73,  78. 

Size,  25. 

Slag,  15. 

Slate,  7. 

Snow,  33. 

»^oap,  119. 

Soda,  120;  soda-lye,  119. 

Soda-water,  30. 

Soot,  31,  32. 

Sparks,  53. 

Spelter  (zinc),  18. 

Spermaceti,  43  ;  sperm  oil,  43,  47. 

Spirits,  of  salt,  120 ;  of  wine,  68 ; 
of  turpentine,  67. 

Sponge,  124. 

Starch,  125. 

Stearine,  44. 

Steel, 80,81;  cleaning,  130 ;  tem- 
pering, 80. 

Straw,  96  ;  straw  paper,  58. 

Sugar,  117;  of  milk,  111. 

Sugar-cane,  117. 

Sulphate,  of  lime,  12 ;  of  iron,  133. 

Sulphide  of  carbon  and  hydro- 
gen, 40. 

Sulphur,  49  ;  sulphuric  acid,  127. 

Sweat,  120. 

Tallow,  41. 

Tan,  tannin,  tanning,  97. 

Tar,  2,  40. 

Tartaric  acid,  103. 

Tartar,  cream  of,  103. 

TttwJQJ,  M. 

Thatch,  13. 

Thistle,  fuller's,  88, 

Threshing,  10ft. 


Tiles,  6. 

Tin,  21 ;  tin-plate,  23. 

Tortoise-shell,  102. 

Tow,  55. 

Train  oil,  47. 

Treacle,  117. 

Tripoli-powder,  130. 

Turpentine,  67  ;  oil  of,  36,  67. 

Type,  printing,  141. 

Varnish,  67. 

Velvet,  90 ;  velveteen,  91. 

Veneer,  37. 

Vinegar,  118. 

Vitriol,  green,  133 ;  oil  of,  127. 

Vulcanite,  102. 

Vulcanised  india-rubber,  102. 

Wadding,  54. 

Wall-papers,  colours  of,  62. 

Warp,  54. 

Wash-leather,  99. 

Water,  30,  32,  33  ;  soft,  33. 

Wax,  bees',  42 ;  sealing,  138. 

Whey,  114. 

White  lead,  59. 

Whitewash,  26  ;  whiting,  26. 

Wick,  32. 

Wicker,  willow,  65. 

Winnowing,  106. 

Wood,  34-36;  sawing  and  season- 
ing, 37;  wood-paper,  58. 

Wool,  54. 

Wool,  animal,  70 ;  cotton,  54. 

Woollen,  70  ;  worsted,  70. 

Wort,  115. 

Writing,  132. 

Yeast,  107. 

Zinc,  (spelter),  15,  18';  plaUs, 
U;  white,  60. 


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#3F./as8f. 


